The full-field heterodyne dynamic interferometer has the advantages of a high measurement accuracy and strong anti-interference ability for surface shape measurement. It is suitable for large-focal length surface shape measurement and the measurement of large-aperture optical elements. However， the performance of the optical components in the interferometer system is not ideal， and there are errors in the assembly of components， which introduce frequency aliasing in the interferometer optical path and affect the measurement accuracy of the interferometer. To analyze the influence of frequency mixing on the measurement accuracy of the full-field heterodyne dynamic interferometer， a theoretical model of the measurement error introduced by frequency mixing is established according to the causes of frequency mixing， and the influence of the frequency mixing degree on the measurement accuracy is analyzed. The results indicate that the measurement error is nonlinearly and positively correlated with the degree of mixing and that the mixing causes a periodic error with the same frequency as the interference fringe on the measured surface shape. In this study， a full-field heterodyne dynamic interferometry experimental system is established to examine the effects of different mixing degrees on the surface measurement accuracy. When the mixing frequency is 0.029， the surface shape measurement error is 0.053λ. When the mixing frequency is 0.120， the surface shape measurement error is 0.110λ. The experimental results are consistent with the simulation results. The research presented in this paper has practical significance for the development of high-precision full-field heterodyne dynamic interferometers.