Aiming at the problem of poor precision and low production efficiency in the processing of the metal base for coarse wavelength division multiplexer,through the technical analysis of the base,the optimization measures of fixture change and processing mode were put forward. It has been proved by practice that the processing efficiency is improved by about 28%,and the qualified rate is increased from 60% to 98%. The new processing technology improves the processing efficiency and the qualified rate of the products,and has a certain practical guiding significance for the processing of microsmall parts.