Abstract: Given that China possesses a large and potential domestic market，we present a heterogeneousagent model examining trade and migration patterns among Chinese regions，and analyze the change in income inequality We quantify the internal and international trade costs，total factor productivity （TFP） and internal migration costs using National Census data and Interprovincial Inputoutput data from 2000 to 2015 Our findings indicate that both internal and international trade costs，as well as internal migration costs，have decreased TFP has shown a trend of first increasing and then decreasing，with regional variations
We quantify the impact of these exogenous shocks on national and provincial economic growth and income distribution in China The results show that the decrease in internal and international trade costs and the change in provincial TFP can promote the growth of real GDP However，these shocks may also exacerbate national income inequality，increasing the Gini coefficient by 0020，0010，and 0109，respectively，between 2000 and 2015 Based on Dagums decomposition，interprovincial income inequality is significantly higher，serving as the primary contributor to national income inequality Furthermore，lower migration costs can reduce interprovincial income inequality，with the Gini coefficient decreasing more substantially when interacting with shocks in trade costs and TFP
We further decompose income into labor and capital income，revealing that under exogenous shocks from trade costs and TFP，both labor and capital income inequality tend to widen across provinces，leading to a general rightward shift in income distribution Simultaneous migration cost shocks can reduce interprovincial inequality Additionally，we classify the provinces into four regions—Eastern，Central，Western，and Northeastern—and find regional heterogeneity We also evaluate the heterogeneous effects at the provincial level
The conclusion suggests that it is important to fully recognize the bidirectional role of internal and international trade shocks，along with TFP shocks，in promoting economic growth while also intensifying income inequality It is essential to leverage the potential of Chinas vast domestic market and continuously promote the construction of a unified national market Concurrently，managing the relationship between economic growth and common prosperity is crucial We offer policy insights with the goal of mitigating income inequality and achieving common prosperity through reducing barriers to migration across regions

Key words: trade costs, migration costs, total factor productivity, income inequality, construction of a unified national market

摘要： 本文构建了一个描述多地区参与国内、国际贸易与人口迁移的异质性个体模型，采用2000—2015年全国人口普查、省间投入产出等数据，测算我国国内、国际贸易成本，全要素生产率（TFP）与国内迁移成本，并分析三者的变动及其对收入不平等的影响。结果表明，虽然贸易成本以及TFP等冲击有助于经济增长，但同时也会加剧全国收入不平等，而迁移成本冲击能够降低收入不平等。基于Dagum基尼系数分解发现，我国省间基尼系数明显增加，然而迁移成本冲击能够显著缓解省间收入不平等，并且在与贸易成本、TFP等冲击交互时作用更大。进一步分析发现，工资收入和资本收入的省间不平等均有扩大的趋势，通过促进人口迁移能够起到缓解作用。此外，外生冲击也存在明显的地区异质性效应。本文结论表明，要充分认识到国内、国际贸易成本以及TFP等冲击对促进经济增长和扩大收入不平等的双向作用，通过打破跨地区的人口迁移壁垒，可以缩小收入不平等、实现共同富裕。

关键词: 贸易成本, 迁移成本, 全要素生产率, 收入不平等, 全国统一大市场建设