In order to avoid the threat of robot collision to construction process and safety, and stimulate the great potential of robots in prefabricated buildings, a laser sensing adaptive trajectory planning method for prefabricated building robots is proposed.The grid map of a prefabricated building is constructed, and the peripheral environment data of the robot is obtained by the laser sensor.The improved A^* algorithm is used to remove redundant nodes, so that the path only includes the beginning, end and key points.The dynamic window and ant colony algorithm are used for local trajectory planning, and the target velocity is calculated to complete the global planning.The experimental results are verified in the grid map of a prefabricated building.In the static grid environment, the proposed method can plan a 38.6m path in 165 iterations and 3.16s.In a dynamic grid environment, this method can avoid dynamic obstacles in 248 iterations and 3.81s.The results show that the path of this method is smoother than that of the literature method[5, 6], and a shorter path can be planned in less time and number of iterations.