本文首先基于Krugman提出的新经济地理学模型，使用国内8大区域和17个行业之间的贸易流量数据，以及各个地级市2007年的地理距离、GDP等数据，通过构建贸易引力模型来测算和衡量各个地级市、省份和区域的市场准入指数（MA），从而发现：（1）不同地级市的市场准入是不同的，甚至会有较大差异；（2）经济越不发达，地理位置越缺乏优势，市场准入的值就越小；（3）地级市的市场准入主要是由城市内部或区域内部的需求拉动的。然后本文基于Samuelson的“冰川成本”模型，使用相对价格法，构造出度量国内市场分割程度的指标，发现1994年以来我国的商品市场分割程度呈现下降趋势，即商品市场趋于一体化，这与大部分已有文献的估算结果基本一致。最后，本文把市场分割程度作为被解释变量，把计算得到的市场准入指数作为主要解释变量，利用1994-2011年的省际数据分析了经济国有化程度、地方政府消费占比、不同地区的技术差距、地理距离、地方政府财政自主度和产业结构趋同对国内市场分割程度的影响。实证分析的结果显示，市场准入指数的估计系数显著为负，说明开放潜力越大的市场，准入门槛越低的市场，地方政府进行市场保护的成本就会越高，从而有利于降低市场的分割程度。此外，经济国有化程度变量的估计系数显著为正，而政府消费占比变量和财政自主度变量的系数估计为负，表明国有化程度越低，地方政府掌握地区资源越多，或者财政自主能力越强，越有利于市场整合。

Firstly, based on the new economic geography model, this paper uses trade flow data of eight major regions and 17 industries in "China regional input-output table in 2007" and gravity model to calculate Markets Access (MA) Index of each prefecture-level cities, provinces and regional, which found that: (1) The value of market access differ from city to city in a relatively large scale; (2) The less developed economy, the worse geographic location, the smaller value of market access; (3) The value of market access of a city is dominated by internal or regional demand.Then based on Samuelson's "Glacial Cost" model, this paper uses the relative price method to construct a measurable indicator of the degree of segmentation in the domestic market. The result shows that the degree of domestic market segmentation has been decreasing since 1994, which means that the commodity market tends to integrate, basically the same as the results in most of the literatures.Finally, this paper takes the degree of domestic market segmentation as the dependent variable, while the market access index as the main explanatory variable, then uses the interprovincial data from 1994 to 2011 to analyze the impact of nationalization, the proportion of local government consumption, technology gap in different regions, geographical distance, the financial autonomy of local governments and industrial structure convergence on the domestic market segmentation. The results of empirical analysis indicate that the estimated coefficient of market access index is significantly negative, meaning that the greater potential of open market, the lower barrier to entry into the market, the higher cost of local government to protect the market, which will help reduce the degree of domestic market segmentation. In addition, the estimated coefficient of nationalization variables is significantly positive, while the proportion of government consumption and financial autonomy of local governments are all negative, indicating that the lower the degree of nationalization, the more resources local government controls, or the stronger financial autonomy local government has, the better market integration will be.