<p>Dimensional deformation and shrinkage porosity are key investment casting defects that typically occur during solidification of the casting at ambient environment after high-temperature pouring. Although these two indicators are caused by various reasons, it is believed that the initial temperature of the shell is one of the dominant factors. This study leverages experiment and simulation methods to reveal the relationship between the temperature drop of ceramic shells and the dimensional deformation and shrinkage porosity of castings in CoCrMo alloy investment casting joints. The experimental results indicate that the insulation conditions of ceramic shells and the filling of high-temperature melt have a significant impact on the temperature drop curve of ceramic shells. The temperature drops of ceramic shells insulated with asbestos are much slower than that of ceramic shells without asbestos insulation, which has a significant impact on the dimensional deformation and shrinkage porosity of castings. Numerical simulation was conducted using a model calibrated for ceramic shell temperature, and the results showed that with the shell preheating temperature increasing from 800 to 1000&#xa0;°C, the total shrinkage volume in the casting decreased from 4.19 to 2.38 cm³, the total displacement of the casting decreased from 1.2 to 1.0 mm, and the gap width decreased from 0.774 to 0.651 mm.</p>