To assess the master conrod structural strength of a star engine， a kinematic and dynamic analysis models of the crank-conrod mechanism was established and the load characteristics was obtained. The finite element model considering structure nonlinear factors was calibrated by the measured stress data from the simulant， and then used to calculate dynamic stress field over the entire operating cycle. The analysis results show that the additional bending moment from slave conrod is the main factor which causes the stress of the dangerous part of master conrod shank to be too high. And then considering the impact of structural factors such as surface technology， the multiple-axle fatigue of master conrod was assessed based on the critical plane approach. The results show that the fatigue safety factor of the transition region between the conrod shank and the big end is relatively low， which has been confirmed by the actual fatigue crack.