A control valve, comprising: a valve body, having a fluid inlet, a fluid outlet, and an inner cavity in fluid communication with the fluid inlet and the fluid outlet; a flow rate presetting assembly, comprising: an adjusting rod, having one end projecting from the bottom of the valve body and another end extending into the inner cavity, the adjusting rod being rotatable around an axis of the adjusting rod; a control component, disposed at a bottom side of the valve body in such a way as to be rotatable around the axis, and connected in a shape-fitted manner to an end of the adjusting rod that projects from the valve body, in order to drive the adjusting rod to rotate; an adjusting component, disposed in the inner cavity and fixedly connected to the adjusting rod, the adjusting component being rotatable between a first position and a second position under the driving action of the adjusting rod, in order to set a maximum degree of opening of the control valve; wherein the control valve further comprises a locking member disposed at the control component, the locking member switching operably between a free position allowing rotation of the control component relative to the valve body and a locked position preventing rotation of the control component relative to the valve body; characterised in that an indicating part is provided on a surface of the control component that faces the valve body and/or on a surface of the control component that faces away from the valve body, and deviation of the indicating part relative to a reference position can indicate a maximum flow rate corresponding to a position of the adjusting component, the reference position being fixed relative to the valve body, and in that the control valve further comprises a removable valve cap disposed at the bottom of the valve body, the valve cap having a through-hole for the adjusting rod to project through, and the valve cap also having multiple tooth parts which are disposed on a surface facing the control component and arranged around the axis; the locking member has a locking part, configured to project toward the valve cap from the control component, wherein, when the locking member is at the locked position, the locking part interferes with the tooth part, thereby preventing rotation of the control component relative to the valve body; and when the locking member is at the free position, the interference between the locking part and the tooth part is released. a valve body, having a fluid inlet, a fluid outlet, and an inner cavity in fluid communication with the fluid inlet and the fluid outlet; a flow rate presetting assembly, comprising: an adjusting rod, having one end projecting from the bottom of the valve body and another end extending into the inner cavity, the adjusting rod being rotatable around an axis of the adjusting rod; a control component, disposed at a bottom side of the valve body in such a way as to be rotatable around the axis, and connected in a shape-fitted manner to an end of the adjusting rod that projects from the valve body, in order to drive the adjusting rod to rotate; an adjusting component, disposed in the inner cavity and fixedly connected to the adjusting rod, the adjusting component being rotatable between a first position and a second position under the driving action of the adjusting rod, in order to set a maximum degree of opening of the control valve; an adjusting rod, having one end projecting from the bottom of the valve body and another end extending into the inner cavity, the adjusting rod being rotatable around an axis of the adjusting rod; a control component, disposed at a bottom side of the valve body in such a way as to be rotatable around the axis, and connected in a shape-fitted manner to an end of the adjusting rod that projects from the valve body, in order to drive the adjusting rod to rotate; an adjusting component, disposed in the inner cavity and fixedly connected to the adjusting rod, the adjusting component being rotatable between a first position and a second position under the driving action of the adjusting rod, in order to set a maximum degree of opening of the control valve; wherein the control valve further comprises a locking member disposed at the control component, the locking member switching operably between a free position allowing rotation of the control component relative to the valve body and a locked position preventing rotation of the control component relative to the valve body; characterised in that an indicating part is provided on a surface of the control component that faces the valve body and/or on a surface of the control component that faces away from the valve body, and deviation of the indicating part relative to a reference position can indicate a maximum flow rate corresponding to a position of the adjusting component, the reference position being fixed relative to the valve body, and in that the control valve further comprises a removable valve cap disposed at the bottom of the valve body, the valve cap having a through-hole for the adjusting rod to project through, and the valve cap also having multiple tooth parts which are disposed on a surface facing the control component and arranged around the axis; the locking member has a locking part, configured to project toward the valve cap from the control component, wherein, when the locking member is at the locked position, the locking part interferes with the tooth part, thereby preventing rotation of the control component relative to the valve body; and when the locking member is at the free position, the interference between the locking part and the tooth part is released.