The invention provides a lane changing control method and device of an autonomous vehicle and belongs to the technical field of automobile electronic control. According to the lane changing control method and device provided by an embodiment of the invention, in case of lane changing, an available region is determined first according a distance between an obstacle and the vehicle and current road condition; when an adjusted guide trajectory is within the available region, steering is available to be prepared, and the problem of steering wheel shaking due to repeated tries of lane changing is avoided; in addition, turn angle of a steering wheel is determined by means of a gradient descent method, the angle of the steering wheel is changed gently during lane changing, the problem that sudden increase in the transverse turn angle due to the traditional preview-follower algorithm leads to poor riding comfort is solved, and riding comfort of the autonomous vehicle is improved.