Much valuable and complete disc cutter wearing data of TB880E TBM used in Qinling tunnel have been accumulated, which can provide reference for further study on disc cutter wearing mechanism. In this paper, the relationship between disc cutter wearing loss and initial rock crushing volume is studied based on disc cutter wearing data and theoretical calculation results of initial rock crushing volume of TB880E TBM. The relationship between the rock crushing volume (mm/m3) and installation radius of disc cutter is analyzed. The disc cutter wearing mechanism of 4 wearing zones on cutterhead are analyzed. The quantitative calculation method for secondary wear of disc cutter induced by repeated rock crushing is proposed for the first time; and then the relationship between repeated rock crushing volume of TB880E TBM and secondary disc cutter wearing is obtained. The study results show that the initial rock crushing is the main factor for the wearing of frontal disc cutter; the repeated rock crushing is the main factor for the secondary wearing of edge disc cutter.