This paper focuses on human factors in maintenance documentation that could be the root cause of human errors. To be proactive, maintenance engineers should explore procedures to prevent maintenance errors during the document preparing process. Then maintenance technicians should follow the documents to complete their tasks in order to reduce human errors. The main purpose of this analysis is to eliminate the potential processes that cause human errors. The involved documents are related to the maintenance process, such as work card and PMDB. Based on the most frequent maintenance human errors, we introduce several analysis principles. Some case studies are used to illustrate the analysis processes and principles as well.