Abstract: Aiming at the problem of straightness detection of scraper conveyor in fully mechanized mining face, the straightness detecting method of a scraper conveyor based on combined inertial navigation is proposed. The combined inertial navigation system consists of strap down inertial navigation, odometer and laser radar. The Kalman filtering algorithm is used to fuse the strap down inertial navigation and odometer information to obtain the straightness detection information of the scraper conveyor. Before the start of each coal cutting, the laser radar technology is used to measure the positional relationship between the two ends of the scraper conveyor and the identification board of the transportation lane and the return airway, in order to calibrate the initial position of strap down inertial navigation system. The straightness detection information of scraper conveyor by laser radar is used to compensate the accumulated error of the position and attitude of the combined positioning method for strap down inertial navigation and odometer after a long time operation. By fitting the detected position information of the shearer, the straightness of the scraper conveyor can be obtained. The straightness detection method of the scraper conveyor was tested in fully mechanized mining face of Huangling Mine. The experiment results indicate that through the information fusion of strap down inertial navigation, odometer and laser radar, the detection error of radar in the advancing direction of working face is less than 0.05 m and the straightness detection error of the scraper conveyor at a 150 m fully mechanized mining face is less than 7 cm. It lays a good foundation for the automatic straightening of hydraulic supports in fully mechanized mining face.