Abstract: The reliability of breech mechanism depends on the strength of extractor directly and affects the warship fighting capacity. Aimed at the extractor yield during extracting process, its topology and shape optimizations were carried out respectively by using HyperWorks software. In order to validate the optimization results, a flexible body dynamics of the breech mechanism was simulated by using ABAQUS software. And, its kinetic energy, internal energy, average extraction speed, strength and stiffness before and after optimization were compared. The analysis results show that the mass of optimized extractor decreases by 20.9%, and its maximal stress decreases by 13% and is lower than the yield limit; the peak of internal energy decreases by 3.44%, and the energy curves are delayed 0.16 millisecond; the trend of kinetic energy is similar to the original one except some fluctuation, the average extraction speed decreases by 0.442% only.