The embodiments of the present invention provide a back frame for installing back light source, a back light source and a display device. The back frame comprises a frame body having an accommodation space for holding a light guide plate; a light source seat detachably connected to said frame body for placing a light source. In the embodiments of the present invention, the light source seat and the frame body are connected detachably so that the light source disposed on the light source seat can be detached from the back frame, which realizes that the light source can be replaced without the need of detaching the display panel, the environment inside the back light source is not destroyed, the material inside the back light source is not harmed or destroyed, thus the replacement cost is reduced and the waste of resources is avoided.