Breech mechanism is the key and important device to improve reliability and maintenance for large caliber guns. It’s major fault mode is grain abrasion caused by dry sliding friction. There is no feasible and practical technologies to simulate and predict the abrasion failure life of key parts for breech mechanism. A new simulation and prediction method is firstly put forward in this paper. Based on Pro/E and ADAMS, the virtual prototype of breech mechanism of semiautomatic vertical sliding-wedge type is established. To validate its precision and effectivity, qualitative and quantitative verification method are adopted to check the virtual prototype of breech mechanism. Virtual prototype produces key parts’ load spectrums and failure theresholds. Dry sliding friction and abrasion experiment provides abrasion rules of typical materials. Finial simulation and prediction results are given as abrasion thresholds and operating items, which provide sufficient references for breech mechanism’s maintenance and safeguard.