To compare the rock breaking performances caused by the arc and wedge hob with two blades, a rock cutting model with two hob blades is established and a series of rock cutting simulations are performed based on the particle flow code. Meanwhile, the rock breaking process, crack extension pattern, rock cutting force and rock cutting efficiency etc. are investigated in this study. The results present that the rock breaking area and the lateral crack length induced by the arc blades is much greater than that induced by the wedge blades. The optimal cutting spacing of the arc and wedge blades is 60 mm and 30 mm respectively. It confirms that the wedge blades can significantly reduce the rock cutting force and raise the rock cutting efficiency compared with the arc blades, which can provide a reference for the hard rock tunneling by the tunnel boring machine.