The serious shield cutter wear is the key to shield boring in sandycobble stratum. In this paper, the composition of shield cutter torque is analyzed in terms of the working principle of earth pressure balance(EPB) shield and the mechanical properties of sandycobble stratum. A calculation model of the friction torque is established by means of mathematical and mechanical analysis. The calculation model is verified on the basis of risk monitoring system of shield tunneling; and the cutter wear degree is tracked and recognized by means of proportionality coefficient, combining with the South Hongpailou StationHongpailou Station on Line No. 3 of Chengdu Metro as an example. The study results show that: 1) The frictional torques on the front of cutterhead, that on the backside of cutterhead and that on the side of cutterhead are the main components of torque of cutterhead when shield boring in sandycobble stratum. 2) The frictional torque model is coincide with the actual construction state. 3) The frictional torque obtained is coincide with the cutter replacing pattern, and can be considered as the recognition reference of cutter wear degree.