中文摘要：

基于中国12个城市1268家工业企业的调查数据，考察了工会对企业工伤事故的影响。研究发现，工会显著减少了企业的工伤事故。利用倾向性得分匹配法考虑了可能的样本选择问题后，进一步研究发现，行业市场占有率较低的企业更可能抵制工会在安全生产和劳动保护方面的活动，使得工会保障职工职业健康安全权益的作用失效。通过考察工会影响企业工伤事故的可能机制考察，发现工会主要通过减少工人超时工作以及争取更多安全培训来降低企业的工伤事故。

英文摘要：

Using the data on 1268 Chinese enterprises covering 12 cities during 2003--2005, we document that union decreases the number of workplace injuries significantly, which means union plays an important role in occupational health and safety. Meanwhile, under the heavier pressure, companies with lower market share tend to resist safe production and labor protection, which makes the protection of unions vain. Furthermore, there are two possible mechanisms which union might have reduced workplace injuries： decreasing overtime work and increasing safety training.