In order to explore the abnormal knocking of the connecting rod bearing of engines from the point of view of dynamics, a certain model engine of military vehicle is taken as object. Hamn′s method is adopted to solve Reynolds equation, and the load and center movement track of the connecting rod bearing is accounted and analyzed in the same lubricating state and under different working conditions, rotation speed, and match clearance. Results show that the pressure measured in the engine cylinder worked on piston top is the main factor of the connecting rod bearing′s load. The horizontal running track becomes larger with increasing match clearance of the bearing, the optimum speed is in the middle (1200～1600r/min), and the optimal diagnosis position is located at the right cylinder blocks facing the bearing.