Abstract: In order to solve the problem that automated fully-mechanized working face is no longer straight after several rounds of cutting coal,the causes of the alignment problem and its influence on automation production are analyzed.The longwall face straightness measuring method based on inertial navigation is proposed.With the inertial navigation device installed in the shearer,it’s 3D trajectory is recorded when it goes back and forth on the scraper conveyer.Principle,algorithm,formula,process of LASC technology are introduced.Based on LASC the working face automatic alignment control system is developed.Verified by both mini-build test on surface and industrial field trial underground,the working face straightness detection error by this system can be less than 100 mm.The whole working face alignment error can be less than 300 mm.It meets the requirement of automatically and continuously retreating fully-machanized working face.