CAE is indispensable in the current field of engineering, and the development of computational mechanics calls for the addition of functions, but by continuing to add functions without taking measures, program complexity and functions Some of the computational mechanics researchers can not afford to take measures or are not familiar with the program, so the laboratory maintains the maintainability of existing programs, By making additional functions independent of each other, research is being conducted on how to add functions that prevent these problems, and this method is advocated as the Option pattern. Maintaining existing program maintainability in the Option pattern. There are three conditions that the additional functions can be made independent and can be combined multiplely, and the additional functions can be described in one place. To. In this study use, by adding a geometric nonlinear functions and dynamic analysis function in FEM program according to the Option pattern, to verify the validity of the function addition method. The class to be added is called Option class, and in this research, four Option classes are added to the existing FEM program. By performing this research, functions are added independently while maintaining the maintainability of the existing program. I was able to confirm that.