The invention belongs to the technical field of the welding of a robot, particularly relates to an autonomous movable type double-wire welding robot system for welding medium plates, comprising a robot body, a control system and a double-wire welding system, wherein the robot body comprises a crawling mechanism and an operation mechanism; the control system comprises a sensing system, a robot body control box and a robot master control system; and the double-wire welding system comprises a double-wire welding gun, a double-wire welding power source, a double-wire wire feeder, and a protecting gas and welding cooling system. The system has the advantage that welded joints can be autonomously identified and tracked. The system has the functions of long-distance welding parameter setting and on-line adjustment and can autonomously identifying the center point of a groove; a multi-free degree cradle head can be adopted, so that the environment monitoring of a workpiece can be realized, the macroscopic operation of an initial point before welding can be completed, and the intelligent welding can be realized; and a molten pool monitoring sensor can be adopted, so that the posture adjustment of the double-wire welding gun can be realized, and the molten pool in the process of welding can be monitored, i.e. the microscopic autonomy can be realized.