The mechanical coupling error is one of main errors of silicon microgyroscopes. In order to provide the theories of decreasing or cancelling the mechanical coupling errors

the mechanism of mechanical coupling errors are studied. Based on the dynamic equations and matrix theory

the anisoelasticity

asymmetrical damping and unbalanced mass of a type of z-axis silicon microgyroscopes were analysed

which are induced with the imperfect machining. The mathematic models of mechanical coupling errors were put forward

and the numerical results of mechanical coupling errors were given. The results show that the mechanical coupling errors include errors in-phase with the useful signals and quadrature errors

and quadrature errors are the largest error among the mechanical coupling errors. And the results indicate the major source of quadrature errors is suspension beams mismatched. Finally

the quadrature error of this z-axis silicon microgyrscope sample was tested. The quadrature error is 342.59 /s

which is in accordance with the analytic results. Restraining and compensating quadrature errors is one key technologies to decrease mechanical coupling errors.