In order to enhance the adaptability of the pipeline of air duct cleaning robot,a new type of adaptive adjust mechanism was presented according to the characteristics of domestic central air conditioning duct,the working theory and mechanical characteristics of the mechanism were analyzed,then the math model was built and the simulation was carried out. In order to increase the maximum walking distance of the robot, the power carrier technology was applied in robot communication system. The carrier circuit diagram was given and the communication protocol was formulated, and the communication process was described,which realized the cable power line and signal line multiplexing. The research results have been applied to the central air duct cleaning robot. The results show that the adjusting mechanism to domestic duct has strong adaptability, and the application of carrier technology increases the robot's maximum walking distance.