KC-100(KAI Civil Aircraft, Small Series) aircraft is 4 seats general aviation aircraft with single piston engine which is developing under FAA part 23 category by Korea Aerospace Industries(KAI) and will be a shadow program for civil aircraft safety infrastructure improvement. This aircraft will be the first civil aircraft developed in Korea meeting the Korean regulatory KAS Part 23 requirements. Type certification for KC-100 aircraft was applied at the second half of this year. The type certificate is expected to be issued after 3 years of design, prototype manufacturing, ground and flight tests. In this paper the system engineering process for civil aircraft was first reviewed. Next, the differences and similarities in the system development between military and civil aircraft were systematically examined using experiences for KAI military aircraft development program.