In order to reduce the number of seabed mining machinery, a counter-rotating drum cutter for excavating Seafloor Massive Sulfide is proposed in this paper. In addition, an attempt was made to simulate the process of counter-rotating drum cutting SMS. For this purpose, a computer software named EDEM based on the discrete element method was used. The micro-properties were calibrated by modeling the uniaxial compressive strength tests and the indirect tensile test. A series of laboratory experiments were carried out. Besides, a cutting model similar to the experiment system was built in EDEM. The torques of drums under different cutting depths were obtained. The experimental and numerical simulation results are consistent, which verified the correctness of the established DEM model. The 3D discrete-element cutting model was established to test the rationality of the counter-rotating drum cutter structure. The influence of the center distance of the two drums and the drum motion parameters on the crushing performance index was analyzed. Moreover, the cutting-load characteristics of the counter-rotating drum and single drum are compared, and it is concluded that the counter-rotating drum cutter reduces cutting resistance.