An infusion cassette of an infusion set, wherein the infusion cassette is provided with a flow channel, and comprises: a rigid assembly comprising a plurality of components (11, 12, 13) stacked onto one another, wherein at least one of the plurality of components (11, 12, 13) is provided with a groove (121, 122); an elastic membrane (14, 15) arranged between two adjacent components of the plurality of components (11, 12, 13) to cover the groove (121, 122) in a sealing manner, wherein the elastic membrane (14, 15) and the groove (121, 122) together form at least a portion of the flow channel; and a locking mechanism, wherein the locking mechanism comprises a mounting frame and a liquid stop plug fixedly arranged on the mounting frame, the liquid stop plug is configured to press the elastic membrane (14, 15) to close the flow channel, the locking mechanism closes or opens the flow channel by means of the liquid stop plug, wherein the mounting frame is movably connected with the rigid assembly to allow the locking mechanism to switch between a closed state in which the flow channel is closed and an open state in which the flow channel is opened, characterized in that the plurality of components (11, 12, 13) comprises a first component, a second component and a third component; the groove (121, 122) comprises a first groove and a second groove; the elastic membrane (14, 15) comprises a first elastic membrane and a second elastic membrane; the second component is arranged between the first component and the third component; the first groove is formed on a side of the second component facing toward the first component, and the first elastic membrane is arranged between the first component and the second component to cover the first groove in a sealing manner; the second groove is formed on a side of the second component away from the first component; the second groove communicates with the first groove and is located downstream of the first groove; the second elastic membrane is arranged between the second component and the third component to cover the second groove in a sealing manner; the liquid stop plug is arranged on a side of the third component away from the second component, and the liquid stop plug is configured to press the second elastic membrane to close the flow channel. a rigid assembly comprising a plurality of components (11, 12, 13) stacked onto one another, wherein at least one of the plurality of components (11, 12, 13) is provided with a groove (121, 122); an elastic membrane (14, 15) arranged between two adjacent components of the plurality of components (11, 12, 13) to cover the groove (121, 122) in a sealing manner, wherein the elastic membrane (14, 15) and the groove (121, 122) together form at least a portion of the flow channel; and a locking mechanism, wherein the locking mechanism comprises a mounting frame and a liquid stop plug fixedly arranged on the mounting frame, the liquid stop plug is configured to press the elastic membrane (14, 15) to close the flow channel, the locking mechanism closes or opens the flow channel by means of the liquid stop plug, wherein the mounting frame is movably connected with the rigid assembly to allow the locking mechanism to switch between a closed state in which the flow channel is closed and an open state in which the flow channel is opened, characterized in that the plurality of components (11, 12, 13) comprises a first component, a second component and a third component; the groove (121, 122) comprises a first groove and a second groove; the elastic membrane (14, 15) comprises a first elastic membrane and a second elastic membrane; the second component is arranged between the first component and the third component; the first groove is formed on a side of the second component facing toward the first component, and the first elastic membrane is arranged between the first component and the second component to cover the first groove in a sealing manner; the second groove is formed on a side of the second component away from the first component; the second groove communicates with the first groove and is located downstream of the first groove; the second elastic membrane is arranged between the second component and the third component to cover the second groove in a sealing manner; the liquid stop plug is arranged on a side of the third component away from the second component, and the liquid stop plug is configured to press the second elastic membrane to close the flow channel.