In order to make up the deficiency of traditional design theory, time-dependent load is loaded on chamber, and continuity assumption, homogenization assumption, isotropy assumption, small transmogrification assumption and plane section assumption are made, then transient dynamic analysis is adopted to analysis the chamber’s strength. Analysis result is according to the theoretical calculation perfectly. Based on the analysis result, using maximum compressive stress and the deformation of chamber as constraints, the chamber’s area is optimized. During optimization, the subproblem approximation method is adopted, while local stress concentration, strong charge are not taken into account in optimization process. Optimization result shows the chamber's thickness can be reduced to 1/3 of original. That means the chamber’s weight can be reduced to 1/9 of original. It’s a good base for the optimization of whole barrel to reduce naval gun’s weight.