This paper uses the quantitative spatial model and China’s inter regional input-output tables in 2012 and 2017 to analyze the characteristics of China’s inter provincial trade cost. The analysis finds that the sources of inter provincial trade costs can be divided into geographical barriers, institutional barriers, and structural barriers. From 2012 to 2017, the inter provincial trade cost in China significantly increased, closely related to the increase in the provincial self-reliance rates, and the increase in the proportion of local service trade. Geographical distance is significantly related to the inter provincial trade cost, and the inter-regional terrain also has a significant impact on the trade cost. The asymmetry of inter provincial trade costs is reflected in the heterogeneity of the input and output provinces, which includes the characteristics of the regional economic structures, the institutional barriers, and so on. The higher self-reliance rate in some provinces reflects their lower level of participation in the domestic division, thus restricts the improvement of the domestic economy integration. In order to promote the construction of a unified national market, it is necessary to focus on the three dimensions trade barriers, actively improve the circulation efficiency, dissolve local separation, and promote spatial labor division and cooperation.