The invention discloses a collecting robot for a tunnel. The collecting robot comprises a moving vehicle body, a peeling conveying device, a collecting box and a local control system, wherein the peeling conveying device, the collecting box and the local control system are installed on the moving vehicle body. The peeling conveying device is used for peeling and collecting marine organisms at thebottom wall of a tunnel and outputting the marine organisms to the collecting box. The local control system includes a local controller, a sensing system and a camera system; the sensing system is used for collecting positional relationship information between the collecting robot, the side wall of the tunnel, and other objects and own state information in real time; and the camera system is configured to collect surrounding visual information in real time and transmit the information to at least one monitoring device. And the local controller can control the moving vehicle body and the peeling conveying device according to information fed by the sensing system or external control. Besides, the invention also discloses a collecting robot system for a tunnel and a control method thereof.