中文摘要：

本文研究两个问题：一是不断深化的进口关税减免对我国企业生产率提升有何影响，二是企业参与加工贸易能否有助于促进企业生产率的提升。一方面，最终产品的进口关税减免强化了企业间在本土市场的竞争，从而有助于提高生产率；另一方面，企业参与加工贸易能得到额外的贸易所得，从而促进企业生产率的增长。通过采用2000-2006年间我国外贸产品的海关数据和规模以上制造业企业生产方面的大型微观数据，本文构建了各企业所面临的关税税率，并精确计算出企业的全要素生产率。基准回归结果显示，关税下降10％，企业生产率会上升大约3％-6％。更重要的是，在考虑企业间由所有权造成的差异性后，发现加工贸易企业相对于非加工贸易企业有更高的生产率。

英文摘要：

This paper explores how processing trade, jointly with tariff reduction, can improve firm productivity. Tariff reductions generate productivity gains via intensified competition. On the other hand, the extra proceeds from processing trade also help improving firms＇ productivity. Using highly disaggregated Chinese product-level trade data and firm-level production data from 2000 to 2006 and constructing firm-level tariffs based on product information, I find that a 10% tariff decrease generates a 3%--6% increase in a firm＇s productivity. In addition, processing firms enjoy significant productivity gains when heterogeneity in firm ownership is controlled for. These findings are robust to various econometric methods, different specifications, and measures of productivity.