The invention discloses a backlight module and a luminous source encapsulation structure thereof. The luminous source encapsulation structure comprises a heat radiating seat, at least one chip and a heat radiating and fixing piece, wherein the heat radiating seat is provided with a combining hole, the dimension of the heat radiating and fixing piece is less than that of the heat radiating seat, and the heat radiating and fixing piece comprises a combining post and a heat radiating fin with a butt surface; the combining post passes through a through hole of a fixing plate and is combined with the combining hole, the butt surface of the heat radiating fin is supported on the fixing plate, therefore, the heat radiating seat and the heat radiating and fixing piece can be stably combined on both sides of the fixing plate in order to ensure the tight binding relation with the fixing plate and increase assembling reliability, meanwhile, the heat radiating fin can be used for increasing the heat radiating effect of the heat radiating seat in extra, and therefore, the heat radiating fin can assuredly help the chip to reduce temperature in order to avoid the work efficiency reduction of the chip and is beneficial to ensuring that the chip stably operates and prolonging the service life.