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 . <EOS>