Multinational corporations pay a certain cost of entry to enter the international market. These costs are often sunk. Neoclassical economics does not consider sunk cost in decision - making， but in the real economy，sunk cost continues to affect business decision significantly， especially strategic shift. In recent years ， with the rise of China ' s labor cost and exchange rate， the international transfer of China' s processing part has aroused widespread concern of scholars both at home and abroad. On the basis of the concept of sunk cost，this article uses modeling and empirical analysis to show that the existance of sunk cost is the reason why the multinational corporations ' decision does not make a timely response to exogenous volatility， and the sunk cost finally leads to the lag of China ' s processing chain in international transfer. This artical also explains the reason why China' s trade processing continues to grow.