Abstract: In order to reduce the work height of working mechanism of WPZ-55/50L coal mine roadway repair machine and improve the adaptability of the roadway, the existing working mechanism was improved. Force analysis is carried out for the new dynamic arm, bucket rod; the stress and strain of the new dynamic arm and bucket rod met the design requirements by mechanics analysis and simulation analysis of finite element software. The application practice shows that the working mechanism is improved reasonably and the action is consistent, which can adapt to the low height of the roadway, meet the requirements of the roadway bottom lifting in coal mine, and provide reliable equipment support for the roadway floor treatment in coal mine.