The invention relates to an automatic conveying device for rice straw. The automatic conveying device comprises two pairs of supporting columns. A U-shaped support is welded to each pair of supporting columns. The two pairs of supporting columns play a role in supporting the two U-shaped supports. A transmission roller is installed in the middle of each U-shaped support through bearings. A conveying belt is arranged between the two transmission rollers on the two U-shaped supports. Conical strips are arranged on the outer wall of the conveying belt at equal intervals. Friction force between the rice straw and the conveying belt can be increased through conical structures of the conical strips, and the rice straw can be smoothly and stably conveyed on the conveying belt through the conical strips. A transmission motor is arranged at the front end of the transmission roller on the left side of the conveying belt through a coupler and installed on a motor supporting plate through a motor base. The automatic conveying device can achieve the automatic rice straw conveying function, manual operation is not needed in the whole process, operation is easy and convenient, and the beneficial effects of the high automation degree, the high work efficiency and the like are achieved.