In the manufacturing process of large size liquid crystal display (LCD), and injection quantity of liquid crystal and the density of Column Spacer (CS) are important factors for minimizing the Mura defects. However, only empirical methods are mainly used for optimizing CS density and LC injection quantity, leading to waste of process material and time and increasing production cost high. In this paper, we proposed mechanical simulation method for calculating the optimal CS density and accurate LC injection quantity. The realistic three dimension structures for full panel by polygon based solid modeling algorithm in order to calculate the desired LC volume, and then performed mechanical simulation with finite element method using the combination of plate bending element and gap spring element. As a result, we reported the optimal LC Injection margin with average cell gap and cell gap deviation according to various thicknesses of CS caused by process variation. We expect that TVolumeX enables panel makers to improve the yield enhancement and reduce production costs, preventing the waste of process materials and empirical experimental time.