The adaptability study of fullface rock tunnel boring machine(TBM) to soft and weak surrounding rock is very important for handling the TBM jamming and support failure induced by surrounding rock deformation. Hence, a series of targeted design schemes for TBM equipment used in Gaoligongshan Tunnel are proposed. A combination design scheme of outward layout of edge disc cutter and reserved overcutting cutter box is proposed, and associates with a suit of synchronous lifting cylinder system and middle guiding column, the lifting and overcutting design of cutterhead is realized. Finally, the overcutting reaches 100 mm along radius direction of cutterhead, and the TBM jamming phenomenon is avoided, which enables TBM longdistance boring in soft surrounding rocks.