With the rapid development of underground utility tunnel, the safety of pipelines is becoming more and more important to ensure the safety of electricity and gas transportation in pipelines. Due to the harsh environment of utility tunnel, manual inspection is inefficient and has great security risks.In order to realize the omnidirectional detection of underground utility tunnel without blind spots, an omnidirectional robot for pipeline detection based on mechanical arm is designed. The mobile robot, mechanical arm, detecting probe are combined into a whole. The robot has the functions of path independent planning, tracking, obstacle avoidance, etc., and detects pipeline leakage through magnetic flux leakage technology, and realizes detection in complex environment through mechanical arm.Experiments show that the integrated robot can carry out omnidirectional detection and has good accuracy in defect identification.