The invention provides an optical assembly positioning structure, an LCD device, and a manufacturing method thereof. The optical assembly positioning structure includes a positioning part and a clamping part used for clamping different optical layers of the optical assembly; a connecting part is arranged between the positioning part and the clamping part, and the positioning part is connected and fixed to one end of the clamping part by the connecting part. The optical layers of the optical assembly of the invention are fixed by separate positioning structures. The positioning part and clamping part of the positioning structure are respectively in contact with the upper and lower surfaces of the optical assembly. The positioning part is fixed and connected to the clamping part by the connecting part. Thus, all optical layers of the optical assembly are clamped and fixed. The optical assembly is assembled firstly, and then the assembled optical assembly is totally fixed in the backlight module, thereby reducing human power; in addition, all the optical layers are integratedly assembled, thereby effectively reducing the relative displacement between the optical layers, and ensuring that large scratch will not be generated between the optical layers.