Abstract: During excavation in hard rock, the disc cutters usually occurred abnormal failure. It is very important to research the influence of cutter geometric parameters on excavation efficiency and cutter load. Based on the Cohesive element, this article established a rock model which used the Cohesive constituted model. The Cohesive constituted model contains double linear constituted evolution and BK damage failure criterion. Compared to the uniaxial compressive strength and Brazilian splitting test, the accuracy and reliability of the Cohesive constituted model had been verified. The linear cutting test and the simulation model of disc cutter excavation was used to research the disc cutter load with different blade thickness, and the effect of blade thickness on rock breaking was comprehensively analyzed in terms of the load curve, volume of rock breaking, and specific energy, etc. The research indicated that there are three main stages of the disc cutter excavation process: the elastic stage, the crack initiation-propagation stage and the rock unloading stage, and the crack initiation-propagation stage determines the rock breaking efficiency. The result indicated that the disc cutter load and rock break volume increases with the increase of penetration and blade thickness, and the specific energy shows a trend of decreasing and then increasing with the blade thickness increase. The specific energy of the disc cutter with a width of 13 mm is the smallest, which means the highest rock breaking efficiency, the disc cutter with 7 mm blade thickness cannot form a through rock fragmentation, the breaking efficiency is lowest.