Abstract: Based on the high vacuum measurement requirements of magnetic confinement fusion operation and the environmental requirements of strong magnetic field irradiation,an optical vacuum measurement method is designed,and the principle of the method is introduced.Combined with theoretical calculation and finite element simulation,the influence of main factors such as temperature,pressure,and vibration on the measurement uncertainty of the optical cavity is simulated and analyzed,and the optimization scheme is proposed.The feasibility of the optical cavity applied to fusion environment measurement is verified.This study provides theoretical guidance and basis for the engineering design of optical resonator and provides a feasible scheme for optimizing and improving the accuracy of measuring devices.