The internal combustion engine is a power generating device. For the machine, the internal combustion engine is its "heart", and the connecting rod plays a role of transmitting force in the internal combustion engine and is one of the most important components in the internal combustion engine. In this paper, the three-dimensional solid model of the cranklink mechanism of single-cylinder four-stroke internal combustion engine is established. It is imported for kinematic simulation analysis. The kinematic and dynamic characteristics of piston and connecting rod in internal combustion engine are observed by post-processing of results. At the same time, a finite element model is established to check the safety factor of static strength and fatigue strength of connecting rod. According to the theory and method of mechanical reliability design, the reliability of connecting rod is analyzed.