This paper presents a method of analysis for facility expansion in GMP(Good Manufacturing Process) industry. For system expansion, analysis model is derived on the special GMP circumstance. The analysis system is simulated for validation for manufacturing system investment. We evaluated system specification for each classified processes for exploration of possibility of system expansion. As a result, an extension system was decided by following proposed process in this study. Also, the model designed for the GMP system was successfully derived for testifying the economic efficiency with discounted payback period method and net present value method. Finally, we could conclude positive result for facility expansion on special circumstance.