In order to solve the phenomenon of the severely uneven vibration magnitude which transferred by the test fixture to the Specimen and reduce the deviation of the acceleration rms value, according to the electric vibration table multi-point control principle and the characteristics of a fixture frequency response, a fixture design optimization model was established. Taking a specimen fixture design as an example, the fixture FRF value was calculated by Nastran software, then the optimal design parameters of fixture was obtained according to the optimization model previously mentioned . Optimization results indicated that the mean square deviation of response acceleration and the acceleration rms variation range obtained the optimization method are all significantly smaller then that with the traditional method, while the vibration test results show that the variation range of the acceleration rms measured on the transfer point in the vibration test is basically the same with the result coming form the optimization calculation. It was proved that the proposed optimization method is feasible and practical, and it can provide a practical and theoretical guidance for fixture design in environmental vibration test.