The main starting valve that is operated by a pneumatic actuator is used to start a diesel engine. It is composed of a ball valve, a check valve, an actuator, etc. In this study, the existing design of a main starting valve is analyzed by the first axiom of axiomatic design theory. The first axiom is introduced to analyze and evaluate the design of a main starting valve. The design parameters (DPs) are determined sequentially by considering the Independence axiom. Then, for the structural design of a main starting valve, the strength is investigated through CFD and structural analyses. In addition, structural optimization of the actuator piston is performed to satisfy the imposed constraint. In this process, metamodels of the maximum stress and weight are built by the Kriging method of interpolation.