Similar to conventional blanking, there are some characteristics, such as rollover, burnish and fracture, on the sides of micro blanked parts. Heights of rollover and fracture vary with the variation of blanking clearance. This paper attempts to reveal the formation of rollover and fracture on the sides of the blanked part made of 3J21 alloy (with strength more than 1900MPa and high elasticity). The effect of blanking clearance on the heights of rollover and fracture of blanked part is studied using the finite element method (FEM). The relationship among stress triaxiality, Lode parameter and equivalent plastic strain to fracture is obtained at different blanking clearances. Based on experimental data, an uncoupling fracture criterion is used to describe the influence of blanking clearances on the fracture height of micro blanked part. The similar method is verified by analyzing the formation of rollover and fracture on brass blanked parts theoretically and experimentally. Therefore, the analysis method proposed in this paper is available to optimize machining parameters of micro blanking to achieve the desired quality of micro blanked part.