The horizontal directional drilling technology is widely used to lay the underground pipelines. These pipelines are of small or medium diameters with a dip angle ranging from 10°to 20°, special pipelines to 30°. In-pipe robot is commonly used to detect the pipeline fault. A new type of telescopic in-pipe robot is designed in this article, which is driven by step motor and screw, and supported by wheels. The robot has advantages of waterproof grade of IP68, stable motion state, and larger traction force. The speed is between telescopic robots and wheeled robots. Through force analysis and calculation, its maximum climbing angle is larger than 35°. The robot has good passing ability through the pipelines with bends. The inertial technology is used to locate the robot under the condition of disturbances. The pipeline fault detection algorithm based on the visual identification technology is designed to detect the pipeline fault. It can not only achieve autonomic positioning but also detect the pipeline fault.