Abstract: Level control arm is key component of trench pipe installation machines actuator.Its structural strength determines operation reliability of complete appliance，and its centroid position affects response speed of level control.Combined with working conditions，based on finite element method，mechanical characteristics of level control arm were obtained through static analysis and transient dynamic analysis.Based on mechanical characteristics，size of level control arm was optimized by defining design variables，constraints and optimization objectives.The analysis results showed that structural stability before optimization was much higher than actual demand.Optimized structure reduced shell thickness，but through data analysis and comparison，structural safety factor remained in a reasonable range.It proved that structure optimization was reasonable.Research methods and results could provide a reference for level control arm of trench pipe installation machines in structural design.