Abstract: In the actual process of precision investment casting, the shell temperature is a key process parameter, which has a certain time-varying disturbance during the transfer of shell, and directly affects the filling, solidification and mechanical properties of castings. Taking the outlet pipe as the research object, the influence of shell transfer time on shell temperature and metal liquid solidification process, and the correlation between shell transfer time and casting shrinkage and porosity defects were discussed. The results indicate that as the shell transfer time increases from 0 s to 720 s, the surface temperature of the shell outside the main shrinkage defect areas decreases from the preheated 950 ℃ to 524 ℃, leading to a five times of increase in the total number of shrinkage defects and a 284.3% increase of total volume. During the transfer process, the temperature of the shell decreases, and the temperature difference between the inside and outside of different wall thicknesses increases, resulting in the temperature difference between the shell and the metal liquid during the pouring process. The solidification time of the casting is shortened,the internal undercooling is insufficient, and the volume and quantity of shrinkage and porosity defects are increased.