A high-pressure in-situ permeation measuring system was developed to evaluate hydrogen permeation properties of polymer sealing materials under hydrogen environments up to 100 MPa. This system could perform real-time monitoring of hydrogen permeation following high-pressure hydrogen injection, employing the volumetric method for quantitative measurement. By utilizing a self-developed permeation-diffusion analysis program, this system enabled precise evaluation of permeation properties, including permeability, diffusivity and solubility. To apply the developed system to high-pressure hydrogen permeation tests, hydrogen permeation properties of ethylene propylene diene monomer (EPDM) materials containing silica fillers, specifically designed for use in high-pressure hydrogen environments, were evaluated. Permeation measurements were conducted under pressure conditions ranging from 5 to 90 MPa. Results showed that as pressure increased, hydrogen permeability and diffusivity decreased while solubility remained constant regardless of pressure. Finally, the reliability of this system was confirmed through uncertainty analysis of permeation measurements, with all results falling within an uncertainty of 10.8%.