This paper analyzes the mainstream theories of international trade and investment，and verdicts their conformance to the international trade and investment activity for offshore oil and gas enterprises in China. Studies suggest that Factor Proportion Theory interprets oil and gas imports well，and the Investment Multiplier Theory in new classical economics framework is the powerful basis theory for domestic investment and foreign investment. Capital Relatively Excessive Accumulation Theory，Technology Innovation and Industry Upgrade Theory and National Competitive Advantage Theory have relatively strong theoretical explanation to outward foreign direct investment （ODI） for enterprises. On this basis，the author constructed the theory of foreign investment advantage of the newly industrialized countries to explain the foreign investment behaviors and paths of the newly industrialized countries，especially the oil companies in China.