Based on the Section 301 investigation report on China in 2018，this paper analyzes impact of the Section 301 investigation on China's industry and the overall economic development with the GTAP model. The evolution of section 301 reflects the shift of American trade policies. Though the frequency of Section 301 investigation has decreased significantly since the establishment of the WTO，the trade protectionism in USA is still relatively strong. Section 301 investigation in 2018 will have a negative impact on the current development of China's various industrial sectors，especially on high and new technology industries，such as China's transportation，electronics，machinery，aviation，information and medicine. Among them，the machinery manufacturing represented by robots，and transportation represented by new energy vehicles，will get most severely damaged. Before China takes countermeasures，the United States will have some improvement in terms of trade balance and social welfare. But if the trade friction escalates，it is bound to have a negative impact on both economies. In addition，trade frictions will raise the social welfare of the major trading partners of China and the United States，and also bring them a different degree of trade deficit.