Tolerances play an important role in modem manufacturing engineering and impact significantly the quality of a product and machining cost. In conventional methods, tolerances design is divided into two separate sequential stages i.e. product tolerance design and process tolerance design. This sequential tolerances design method would result in some problems in cooperation, continuity, and consistency between two separate design stages. A more rational approach in tolerance design is concurrent tolerancing which consolidate the two sequential design stages into one. In this paper, a genetic algorithm (GA) is used for concurrent tolerance design based on manufacturing cost and quality loss. A practical example is used to illustrate the design process. The calculation results by using CA are compared with those by conventional nonlinear optimization method.