This paper uses the marginal cost model to estimate international market power of China’s iron and steel industry and finds that international market forces of China’s iron and steel industry have dropped after joining the WTO, and international market forces of China’s iron and steel industry were small before and after China’s joining the WTO. Then it selects the iron and steel of the SITC (Rev.2) 67 and uses the expand residual demand elasticity model to empirically study their international market forces in the Republic of Korea, India, Japan and the United States. It is found that market forces are in turn reduced in the Republic of Korea, Japanese and Indian markets, and market forces have not yet formed in the U.S. market. It indicates that China’s iron and steel products export has a certain amount of international market forces, and the ratio of export price and import price tends to decrease and low-cost advantages have gradually weakened. Comparative interests in trade obtained by China’s iron and steel products have gradually reduced. Real international market forces of China’s iron and steel products are not obvious