In order to solve the problem that it is difficult to measure the internal temperature and pressure parameters of large size samples in the current in-situ environmental simulation test of deep earth, a sensor sealing device applied to the geotechnical mechanics test system is designed. By prefabricating the device inside the sample and sealing the sensor components, direct contact between the sensor, the back-end wire and the high-temperature and high-pressure environment is avoided, and accurate measurement of temperature and pressure parameters inside the sample can be achieved. The verification test shows that the addition of this device does not disrupt the experimental environment where temperature, pressure, and oil coexist inside the triaxial chamber. The proposed device not only provides a guarantee for stable measurement of large-sized specimen mechanical tests, but also improves the accuracy and reliability of measurement. Due to the good sealing performance and resistance to high temperature and high pressure conditions of the device, slight improvements can be made and it can be used for operations in complex environments such as deep sea and deep space, which has broad application prospects.