The purpose of this study is to verify factors in building a navy in China. One of the theoretical backgrounds is the category of the threat environment, which includes arms race model, the balance of power theory and the threat of the balance theory. Another theoretical background is the category of the will of the top leader, which includes the strategic choice theory. Based on the aforementioned theories, I have inferred three factors: threat environment, economic power, and strategic choice of leaders. I have anayzed Deng Xiaoping period for China. The results of study are summarized as follows. During the period of Deng Xiaoping, both the threat strength and the economic power were strong and the top leader had positive will to build naval power. As a result, China reinforced the naval power and evolved from littoral water navy to off-shore navy. As a result of the study, I have found that the threat environment and the economic power and the strategic choice of the leaders became an essential factors for the building naval power. In other words, the attitude of leaders toward the building naval power played the most significant role. This is because the top of leader recognizes the characteristics and strength of threats, and invests its economic power, and then makes a strategic decision. In theory, the three factors individually affect the building naval power, but in reality the three factors have a cross-effect on the national strategic choice of building naval power. That is, the national strategic choice results in the building naval power. China during the Deng Xiaoping period diminished the military power in all branches of the services and armament substantially in order to grow its economy. The top of executives of the China concentrated on the building of a navy, but the naval man power was reduced in the same manner that other service members were. Deng Xiaoping invested the armaments into building a naval force. As a result, China took advantage of naval force as a deterrent force against Russia and the US, which were real threat, and potential threat, to them respectively. One of the key features from the military reform process, the curtailment of the naval power in China was relatively small when compared to the other services of their military system. it resulted from the fact that the top executives in China was aware of usefulness of the naval power.