Urban pipeline system is the core infrastructure of water supply, drainage and natural gas transmission. However, the blockage and damage of pipelines may cause serious environmental pollution and urban operation risks. To this end, the project designed a robot with cleaning and inspection functions to deal with the limitations of traditional manual maintenance of pipelines. The robot adopts a three-support wheel structure, which can move flexibly in the pipeline within a certain size range, and realize the adaptive adjustment of the pipe diameter through the electric push rod. The realization of the robot function adopts the modular design idea. The robot can be equipped with a rotating tool to efficiently clean the blockage and sediment in the pipeline, and can be equipped with an infrared thermal imaging module to accurately detect the damage in the pipeline. The modular design enables the robot to replace the functional modules according to the task requirements and realize the diversified operation ability. Through kinematics simulation and finite element analysis, the rationality and reliability of the mechanical structure of the robot are verified. The prototype of the robot is made and the experimental test shows that the robot can operate stably in the complex pipeline environment, and has good passability, cleaning ability and pipeline defect detection ability, which provides an efficient and intelligent solution for urban pipeline maintenance and has broad application prospects.