Applying JIT(Just-In-Time) production system to strength competitiveness power and renovate managent has problems. This study is proposed to solve one of the problems, that mother company has different production system with subcontractor, in order to connect production system of mother company with subcontractor. In the view of the Pull System, production system of mother company, it is possible that the more smoothed production planning is established by developing the algorithm the smoothed production planning preserving the LOTproduction system and comparing the existing research. Also, in the view of subcontractor taking Push System, the possibility of keeping delivery and improving productivity is proved using simulation technique by changing Job shop to GT Cell production system because demand is fluctuating.