Abstract: In order to study the capability of the main insulation materials of the ocean energy generators under salt spray and humidity thermal ageing condition, the test for the resin-rich molding (RRM) tong-ma epoxy glass fiber power mica (TEGM) insulation materials was carried out under the simulated ocean climatic condition. The water absorption rate of the resin-rich molding insulation materials was measured under different ageing cycles. The surface morphology change before and after the ageing test was analyzed based on the observed results of the sample through the scanning electron microscope (SEM). The frequency dielectric characteristics of the TEGM insulation materials were measured by the broadband dielectric spectrometer at different ageing cycles and different measuring temperatures. The relationships of the microstructure variety and the macroscopic dielectric property were analyzed by the dielectric polarization theory. The results show that the water absorption rate of the TEGM insulation materials sample appears three stages, namely fast absorption stage, slow absorption stage and saturation absorption stage. The relative dielectric constant and loss factor show the rising tendency with the increasing ageing time, and the frequency domain spectroscopy (FDS) curve can reflect the insulation ageing state directly in the low frequency range. Through the curve fitting of measured data, it can be seen that there are the quadratic equation relationships between the dielectric parameters and the water absorption for the aging insulation materials in the low frequency range.