The sea around China is rich in oil and natural gas. While most of China's oil import depends on sea transportation, ocean provided the important resource of energy and has become the life-line of China's national development. There are two opinions concerning the issues about China's oceanic geostrategy and oil security: First, China should enhance the cooperation with other countries to keep peace, without emphasizing military power. Second, building up a strong Navy is the only way to acquire the command of sea. The study finds that since the oil security of China still controlled by other states, thus how to gain the superiority in oceanic geostrategy, and to handle the resource of oil and natural gas around the sea is the best way to solve the problem of China's oil security.