Optical board and back light module unit

An optical plate used for a backlight model with a framework includes a main body including a light incoming surface and a light emitting surface opposite to the light incoming surface. The optical plate further includes a fixing part extending outwards from an end part of the main body, and the fixing part is used for being fixed with the framework. The invention further provides the backlight model using the optical plate and having the advantages of assembly difficulty reduction and low cost.