Abstract: This paper focuses on the fatigue failure problem of the master connecting rod of a stern motor radial aero-engine with nine cylinders.Kinematics and dynamics analyses are combined to obtain the maximum moment on the rod during working cycle.As surface loads on the rod are transferred through motion pairs,the contact element in ANSYS is used to simulate the contact situation between the master connecting rod and crank pin or piston pin.A finite element analysis is conducted for the rod.The results of the finite element analysis show that the fatigue strength reserve of the rod is not sufficient.The coincidence of danger position and failure position gives a good reference for the analysis of rod fatigue failure.