The present disclosure relates to a transmission mechanism, a driving mechanism assembly, and a mobile terminal. The mobile terminal includes: a shell including a first mounting face and second mounting face opposite the first mounting, and a side face, the first mounting face defining an accommodation groove extending to the side face along a first direction; a camera mounting assembly, including a mounting seat and a camera, wherein the mounting seat is arranged in the accommodation groove; and a driving mechanism assembly, including a driver coupled to the shell and a transmission mechanism, the driver is movable to drive, by the transmission mechanism, the mounting seat to extend from the accommodation groove and capable of driving the mounting seat to rotate around a rotating shaft and the rotating shaft being parallel to the first direction.