Division and collaboration with supporting enterprises will enable leading enterprises to enjoy the efficiency brought by specialized production, but it could also make their innovation knowledge spillover passively as a result of supporting enterprises’ leakage. So, there are two forms of division structure between leading enterprise and its supporting enterprises: open and closed. The choice bases on the innovation pattern among leading enterprises, while the key factor is the leaking probability of supporting enterprises. The case of Taizhou sewing equipment industry cluster shows that, under the condition of complementary innovation among leading enterprises, the probability would be higher when the supporting networks of leading enterprises overlapped each other, and then leading enterprise chose open division structure, otherwise chose the closed. And the degree of overlap influenced by the spatial distribution of the leading enterprises within the cluster. In addition, the knowledge protection atmosphere of the cluster has a certain impact on the leaking probability. Meanwhile, the case also illustrates that the different division structure has different effect on the development of enterprises.