In the high resolution color CRT, it is very important to suppress the color purity drift casued by thermal deformation of shadow mask. Therefore, it is meaningful to simulate the thermal deformation of shadow mask when temperature rises up in complex CRT operation. In this thesis, new shadow mask model based on linear elasticity theory and minimum potential energy principle is developed. And then, shadow mask thermal deformation is simulated numerically form the new shadow mask model with real color CRT mask data and temperature distribution of the steady state at which no more thermal deformation occurs. Two parameters of deformation are of our interest: doming of the curved plate and deformation of aperture holes. We discretize the shadow mask model into a finite number of shell element and apply the finite element method to simulate them. The finite number of shadow mask displacement, so-called nodal point displacement, by thermal deformation is calculated using, SAP90, one of the famous package for finite element method. From the calculated nodal point displacements, the deformed shadow mask shape considering two parameters can be reconstructed by interpolation. The beam landing shift data measured in the literature is used as a master data set to verify the simulation results.