In order to ensure the safety and reliability of the optical microphone in the internal application of electrical equipment,polyurethane,polytetrafluoroethylene,epoxy resin,polyetheretherketone and phenol-formaldehyde resin are selected as packaging materials to carry out environmental compatibility tests related to electrical equipment and test material properties before and after the tests by scanning electron microscope (SEM) and Fourier transform infrared (FTIR) spectrometer. The results show that the polyurethane surfaces are susceptible to infiltration of transformer oil and have a marked colour change. It can be used in the environment of hydrophone,air and ambient temperature,but not in the environment of oil-immersed transformer. The polytetrafluoroethylene is compatible with the transformer oil,and can be used in the environment of oil-immersed transformer,gas insulated switchgear (GIS) and environment with large temperature change. The compatibility of other materials in electrical equipment related environments is not good,and their applicability needs further research. A method for testing the environmental compatibility of packaging materials is presented in this paper. It can be used for reference in the selection of packaging materials for optical microphones and has certain engineering practical value.