The equation of vulcanization reaction rate of additive liquid silicone rubber is established by experiment, then the mathematical model of vulcanization ratio is constructed. The new concept of increment of vulcanization ratio is introduced, so the numerical analysis of vulcanization ratio is done. According to statistical theory, the numerical computation expressions of crosslinking structure parameters are derived, while the original molecules are distributed in Flory manner. Handling the reaction heat by the way of internal heat source, the partial differential equation of heat transfer is established in the vulcanization molding area, and necessary approximate treatments are done as well. Adopting weighted margin method, the foundational control equations for calculating the temperature field are derived, and two types of thermal boundary conditions are tackled. On the foundation, the numerical simulation theory of vulcanization molding can be studied, and the computer-aided engineering software of vulcanization molding can be designed.