Abstract: The paper analyzed main methods of straightness control of fully-mechanized coal mining face and introduced working principle of straightness control. It used laser alignment sensor to design straightness control system in coal mining face, so as to achieve straightness control of hydraulic support. Underground principle experiment results show that the system can effectively control relative position of supports along the working face direction, and straightness control precision reaches 30 mm, which can meet requirements of straightness control of coal mining face.