Abstract: An active helical drive in-pipe robot is proposed to solve the problems of the passive helical drive in-pipe robots such as small tractive force and low mechanical transmission efficiency. Comparative analysis on kinematics and mechanics is accomplished between active and passive helical drives. The difference between the two drive methods is explained theoretically. Structure design, control system design, prototype development and performance tests are completed as well. Experimental results show that the tractive force of the active helical drive in-pipe robot is much larger than that of the passive helical drive in-pipe robot. The active helical drive in-pipe robot has compact structure and big tractive force, and can adapt to the narrow pipeline operations better.