本文关注的是中国进口关税对于进口金额、数量的影响，基于2002-2017年中国产品层面贸易及关税数据进行实证检验。首先进行描述性统计分析，本文探究了关税与进口相关性、中国进口总量结构及关税变动趋势等三个方面，考察了进口多样性、商品结构、来源国分布、关税率和征税范围等不同维度的指标。第二，在国际经济学理论和进口需求模型的基础上，基于2002-2017年产品层面数据实证检验了关税变动对于总体进口的影响，进口因变量及关税指标均采用多种不同衡量方式。结论发现关税降低能够提升进口金额及数量，且数量对关税弹性的绝对值大于金额。第三，根据世界海关组织（WCO）商品大类、联合国广泛经济类别（BEC）分类及国民经济行业三种不同标准划分子样本进行回归分析。根据商品特征分类，对于电气机械、矿物和化工等进口占比较大的商品类别，关税降低可以显著提升进口，这一效应对纺织品、金属等则不明显；根据生产阶段分类，关税降低可以显著提升初级品、消费品和资本品进口，而加工中间品进口对关税则不敏感。此外本文测算了进口关税弹性和福利效应，结论发现矿物等初级中间品以及运输设备类的关税弹性较大，初级品关税下降1%可提升进口3%-5%，降低关税带来的福利提升比较明显。第四，考虑了关税与进口之间的交叉影响，即某种产品关税变动可能会对其他产品进口造成影响。本文发现在总体层面不存在显著的外溢效应；但划分子样本后，对于中间品和消费品，一种商品关税的提高会促进其他同类商品的进口、替代性较明显，而资本品之间的互补性较为突出。第五，本文扩展考虑了非关税贸易壁垒的影响，对几种主要形式进行了分析；此外构造行业进口渗透率作为回归自变量，结论发现其与产品层面进口存在显著正向关系，相对于金额，非关税贸易壁垒对进口数量的影响更为突出。此外，本文通过更换指标、加入滞后项以及延长数据区间等方式，进行了一系列稳健性检验，发现基准结果仍保持稳定。

Based on Chinese product-level data, this paper focuses on the relationship between import tariffs and imports. First, this paper uses descriptive statistical analysis to explore the correlation between tariffs and imports, the structure of Chinese imports as well as the growing trend of import tariffs. Second, based on economic theories and import demand function, this paper investigates the relationship between tariffs and imports empirically with product-level data from 2002 to 2017. Import variables and tariff rates are measured by diversified indicators. The conclusion is that tariff reductions can improve the values and quantities of imports. Third, this paper divides the whole sample into several subsamples according to three different classification systems --- World Customs Organization （WCO） classification, Broad Economic Classification （BEC） and National Industries Classification. As for commodity features, for products belonging to such categories like electric apparatus and mineral, the positive impacts on imports of tariff reductions are significant. In terms of production phase, tariff reductions can enhance the imports of primary, consumption and capital goods but not those of processed intermediate inputs. This paper further calculates the tariff elasticity of imports for each commodity category or industry. The elasticity of primary goods and transportation equipment are largest, bringing the most significant welfare gains. Fourth, this paper also considers cross impacts or spillover effects, namely the tariff reductions of one product may have influences on other products. According to empirical tests, there exists no significant spillover effects for the whole sample. But for some subsamples, the tariff reductions of one product can restrain the imports of others, while some subsamples show the opposite results. Finally, non-tariff barriers are taken into consideration. Besides, a series of robustness checks prove the stability of benchmark results.