In policy and reality, China’s imports and exports are undergoing great historical changes. China’s foreign trade policy has experienced changes from "rewarding export and limiting import" to "high-quality import and export " and then to "promoting high-quality development of foreign trade". In promoting the high-quality development of foreign trade, the financing environment is one of the important influencing factors. From a financial point of view, we need to know, in different historical periods, whether bank loans can promote foreign trade, how loan costs affect import and export and what are the different impacts on foreign-invested enterprises and non-foreign-invested enterprises? Based on the World Bank Investment Climate Survey in 2005 and Enterprise Survey in 2012, this paper examines the historical changes of bank credit affecting the export and the import of intermediate inputs of Chinese enterprises, and also examines the differences of these changes among enterprises with different ownership natures. It is found that, on the whole, the positive influence of bank credit on the extensive margin and intensive margin of import and export is increasing. On the extensive margin, the positive impact of collateral loans and unsecured loans on export participation is significantly enhanced. On the intensive margin of export, the impact of collateral loans and unsecured loans on direct exports value has not changed significantly, but collateral loans have significantly increased the proportion of direct exports. In 2003, collateral loans significantly increased the proportion of imported intermediate inputs used by enterprises, and in 2011, unsecured loans played this role. The test results of the whole sample more reflect the impact of bank credit on non-foreign-invested enterprises. The positive impact is highlighted in that low-cost loans replace high-cost loans to promote the export and import participation and increase the proportion of imported intermediate inputs. This supports the transformation of international trade from focusing on price to focusing on quality. The adverse effects are mainly manifested in the fact that the higher loan cost urges non-foreign-invested enterprises to reduce the supply in the domestic market. Their export value has not increased significantly while the proportion of exports has not. This means that under the high pressure of repaying loans, enterprises are restricted in the dilemma of exporting in order to alleviate financing constraints, and the export mode is difficult to upgrade. China should continue to promote banking reform, improve the financing environment, and effectively reduce the financing costs of local enterprises. On the one hand, it can change the low-quality export of enterprises to alleviate financing constraints, correct excessive export orientation, and urge enterprises to serve the domestic market; On the other hand, it can promote the import of higher-quality intermediate inputs, improve productivity and product quality, and promote the high-quality development of foreign trade.