In petrochemical and pipeline construction industries, crawling robots in pipelines have been rapidly developed and applied. According to the characteristics of the largediameter oil and gas pipeline, the working conditions for the internal crawler robot were analyzed, and an internal crawler nozzle assembly paired robot with a diameter of 1 422 mm driven by compressed air was designed. Remote control mode was adopted for the robot,by which forward, backward, emergency stop, tightening counterparts operations could be realized. Hightorque pneumatic motor on both sides and fourwheel drive were adopted.The robot had strong climbing ability, and could be applied to largeslope construction conditions. Through function expansion, functions such as inpipe monitoring and equipment maintenance could also be implemented.The mechanical structure, control flow and control principle of the crawling robot used in the pipeline were introduced. The robot has the advantages of strong expansion performance, good crawling ability, safety and environmental protection, and simple operation control.