New structure of grooved fixture with cambered surface is proposed to reduce wear of bar surface caused by fixture in low-stress cropping. The influence of fixture contact parameters and surface quality on wear characteristics of fixture-bar friction pair is researched by using FEM and orthogonal experiment. The radial wear degree is proposed to evaluate the wear degree of bars under four contact conditions, and the wear mechanism of the friction pair is analyzed by SEM. AE-stress-strain cropping platform is established to research the influence of roughness on the comprehensive wear state of the friction pair. Results indicate that the friction pair under A4B1C2D1E4 combination of contact parameters has the best wear reduction effect and lowest radial wear degree which is 0.0469mm2 and 34.50% lower than one of line contact. AE characteristic parameters curves reflect that under different contact condition, when Ra=0.4μm, the values of AE characteristic parameters are all the minimum and comprehensive wear state of the friction pair is the best.