The utility model belongs to the field of underwater robot engineering, and particularly relates to an underwater electric mechanical arm clamp structure. The underwater electric mechanical arm clamp structure comprises a clamping driver module, a cam, a guide plate, cam driven members, a clamp A, a clamp B and transmission bolt bearings. The cam is mounted at the output end of the clamping driver module, arc-shaped grooves are formed in the cam, and the transmission bolt bearings are arranged in the arc-shaped grooves. The clamp A and the clamp B are connected with the transmission bolt bearing A on the cam through the cam driven member A and the cam driven member B respectively, the periphery of the cam driven member A and the periphery of the cam driven member B are provided with guiding devices which are mounted on the clamping driver module and used for limiting rotation of the cam driven member A and rotation of the cam driven member B, and the cam is driven by the clamping driver module to rotate. The transmission bolt bearings on the cam can make linear motion in the arc-shaped grooves in the rotating process of the cam, so that the clamp A and the clamp B are opened or closed. The underwater electric mechanical arm clamp structure has the advantages of being novel and compact in structure, convenient to disassemble, complete in function, capable of conducting deep sea operations and the like.