Abstract: The Japanese fuel behavior analysis code FEMAXI Ⅳ provided by OECD is used to calculate the stress level of Qinshan Nuclear Power Plant fuel rod under pellet clad mechanical interaction (PCMI) and to evaluate the safety margin of PCMI. The threshold of rod power is obtained after the determination of threshold of local hoop stress. The safety margin of linear power is 147 W/cm and the safety margin of local hoop stress is 263 MPa under the accident condition of unanticipated control rod withdrawing according to the threshold.