Electrical penetration assembly (EPA) is a specially electrical equipment in nuclear reactors. Glassmetal sealed EPA is used in the fourthgeneration nuclear reactors because of its excellent sealing performance, high temperature resistance and long service life. The sealing performance of EPA is closely related to the magnitude of stress in glass. Sufficient stress is the key factor to achieve effective sealing in harsh environment. The valid analytical measurement of stress has always been the main topic. In this review, the structure of EPA was introduced. And the influence of stress on glassmetal sealing was explained. The magnitude of stress determines the pressure resistance ability of glassmetal interface and affects the service life of EPA. In addition, the research progresses of various measurement methods of stress in glassmetal sealing including indentation technology, fiber Bragg grating technology and photoluminescence spectroscopy technique were elaborated. Moreover, the application of the finite element simulation method in characterizing stress was reviewed. Finally, the possible future research direction was proposed.