Abstract: Based on the failure physical reliability theory, the stress condition of the driving gear of the rotary screen under three operating conditions is simulated by using the transient dynamics method, the gear stress weak position is identified as tooth root position, and the tooth root equivalent stress is basically the same under three conditions, The reliability fatigue life calculation method based on the stress-strength interference theory is used to calculate the reliability life of the driving gear. The Miner linear damage accumulation theory is used to establish the constraint equation of reliable operation condition and cycle calculation, which provides input for the formulation of preventive replacement cycle of equipment. The results show that when the reliability is 0.95, two gear feeding cycles are reasonably safe and can be extended to 4 feeding cycles, fatigue damage of gear is positively correlated with rotational speed, and high speed running time should be strictly monitored.