This paper is based on the perspective of financial security and national interests． Firstly，according to the theory of foreign exchange reserves demand，foreign exchange reserves are divided into financial security reserves and national interest reserves． Secondly，the paper introduces the safety first criterion and constructs the foreign exchange reserve optimization model based on the financial security． Thirdly，by calculating the theoretical model and numerical simulation，the financial security scale and the national interest scale of the foreign exchange reserves are calculated，and the allocation of the foreign exchange reserves is optimized． The paper shows that China can use about 65% of its foreign exchange reserves to meet the financial security， while the remaining 35% can be used to achieve national interests． This paper agrees that foreign exchange reserves， as the national financial assets，should be mainly used to safeguard national financial security and achieve national strategic interests and economic interests． By docking“The Belt and Ｒoad”strategy，foreign exchange reserves can support the internationalization of the ＲMB and the enterprises to“go out”，as well as the promotion of foreign direct investment and national strategy，to achieve the maximization of national interests． At the same time，excessive foreign exchange reserves can be reduced automatically． Therefore，in the current foreign exchange reserves management，the scale of the foreign exchange reserves is not the focus of discussion． The management departments should not actively curb the growth of foreign exchange reserves，butshould pay more attention to how to improve their efficiency．