A backlight module, comprising: a back frame, comprising a side wall and a bottom wall, wherein the side wall and the bottom wall are bent to connect to each other and define a receiving space; an optical assembly, arranged on the bottom wall and received in the receiving space, wherein the optical assembly comprises a light guide plate, and the light guide plate defines a recess; a backlight source, comprising a lamp and a flexible circuit board, wherein the lamp is arranged on and extends along a side of the light guide plate close to the side wall; and a positioning member, arranged to connect to the back frame and at least partially received in the receiving space, wherein the positioning member comprises a positioning portion, the positioning portion is a protrusion having a shape corresponding to the recess and engaged into the recess, and an extending direction of the positioning portion is parallel to an extending direction of the lamp, such that a distance between the light guide plate and the backlight source is less than or equal to a threshold; wherein the positioning member further comprises a body portion and an extension portion, the body portion is connected to the back frame, the extension portion is arranged to extend from the body portion towards the positioning portion in the receiving space, and the positioning portion is arranged on the extension portion; the side wall comprises at least two side walls, the at least two side walls are bent to connect to each other, the body portion is arranged at a position at which the at least two side walls are connected to each other, and the extension portion is arranged to extend from the body portion at a position between the light guide plate and at least one of the at least two side walls. a back frame, comprising a side wall and a bottom wall, wherein the side wall and the bottom wall are bent to connect to each other and define a receiving space; an optical assembly, arranged on the bottom wall and received in the receiving space, wherein the optical assembly comprises a light guide plate, and the light guide plate defines a recess; a backlight source, comprising a lamp and a flexible circuit board, wherein the lamp is arranged on and extends along a side of the light guide plate close to the side wall; and a positioning member, arranged to connect to the back frame and at least partially received in the receiving space, wherein the positioning member comprises a positioning portion, the positioning portion is a protrusion having a shape corresponding to the recess and engaged into the recess, and an extending direction of the positioning portion is parallel to an extending direction of the lamp, such that a distance between the light guide plate and the backlight source is less than or equal to a threshold; wherein the positioning member further comprises a body portion and an extension portion, the body portion is connected to the back frame, the extension portion is arranged to extend from the body portion towards the positioning portion in the receiving space, and the positioning portion is arranged on the extension portion; the side wall comprises at least two side walls, the at least two side walls are bent to connect to each other, the body portion is arranged at a position at which the at least two side walls are connected to each other, and the extension portion is arranged to extend from the body portion at a position between the light guide plate and at least one of the at least two side walls.