Abstract: There always exists human error in lots of dam break accidents at present. The reaserches on dam break in water conservancy projects are often focused on engineering factors， and little is done on human error. Human factors in 3500 dam break accidents from 1954 to 2010 in our country are studied in the paper， 14 dam break accidents including dam break events of Banqiao reservoir， Gouhou reservoir， Xiaohaizi reservoir and so on are analyzed， and the interior rules and relations among them are investigated. The analysis results show that technology shortage， violation of reseroir operation rules， insufficient experience， lack of job responsibility and poor preventive sense are the main causes of the human error. These analysis results can give a positive reference to the managerial staff engaged in the safety management of reservoirs.