The present invention provides a light guide plate and a manufacturing method thereof. The manufacturing method firstly forms a plurality of spherical recesses arranged at intervals on a light-emitting surface of a light guide plate body when the light guide plate body is formed by pressing, and then applies a diffuser particle with corresponding shape on a surface of each of the spherical recesses, so as to complete the manufacture of the light guide plate. When being mounted in a backlight module, the light guide plate benefits the backlight module of reducing the use of diffuser films, so as to reduce the thickness and weight of the backlight module.