In view of the problems that traditional sealing method easily leads to pouring liquid leakage and the model has large size error when casting photoelastic models,a new sealing method was proposed,which adopts the same sealing material and casting process as the mold to seal up.The gear photoelastic model casting experiment indicates that by applying the same sealing material and casting process,the sealing layer and the mold can form a whole,which can suffer different temperature and pressure without stripped off,and can effectively avoid the liquid leakage in the casting process.The thickness of the sealing layer is 05~15 times of the thinnest place in the mold wall.This indicates the layer has very small fastening force,which allows the model expand and contract isotropically and make the model’s additional deformation level reduced.The experiment results show that,by applying the new sealing method,the underfeeding phenomenon of photoelastic model is avoided,the maximum size errors of the inner circle diameter and height of the manufactured gear are both less than 2%.The Model dimension accuracy meets the requirements of photoelastic tests.