The invention discloses a self-unloading truck and a door opening mechanism of the self-unloading truck. The door opening mechanism of the self-unloading truck comprises a lifting mechanism, a transmission mechanism and a rear compartment sliding mechanism. The lifting mechanism supplies power to opening and closing of a rear compartment. The transmission mechanism comprises a transmission wheel and a transmission part. The transmission wheel is fixedly connected with the lifting end of the lifting mechanism. The middle of the transmission part is wound around the transmission wheel. One end of the transmission part is fixed to a side compartment of the self-unloading truck, and the other end of the transmission part is fixed to the bottom of the rear compartment. The rear compartment sliding mechanism is arranged between the side compartment and the rear compartment so that the compartment can perform lifting unloading after the rear compartment slides upwards to be opened and the rear compartment can slide downwards to be closed when the compartment falls back after unloading. According to the self-unloading truck and the door opening mechanism of the self-unloading truck, the technical problem that the rear compartment collides with materials on the ground due to the fact that the compartment is lifted is solved. Besides, the unloading efficiency of the compartment of the self-unloading truck is effectively enhanced, and the stability and the safety in the automatic material unloading process are improved.