Abstract: Based on the multidisciplinary design optimization, a multidisciplinary variable coupling design optimization method for non-hierarchic systems was presented, and its basic ideas and working principle were given. To handle the coupling between subsystems, a coupling function was established by the ideal point during system-level coordination, which was used to coordinate independent optimization of the subsystem and finally obtain the global optimal solution. The method was proved by being used in the design of a comb-finger microaccelerometer.