The invention relates to a moving robot obstacle avoiding method based on a laser range finder, which comprises the following steps: building the coordinate system of the robot; with the current location of the robot as a center of a circle, simulating laser transmission at the origin of coordinates to transmit N laser beams of which the directions are determined as candidate directions of the motion of the robot; dividing laser information into groups, selecting an obstacle point in each group, and mapping the obstacle point into the coordinate system of the robot; expanding the robot into acircle with a radius of R, drawing two tangent lines of the circle through one obstacle point, working out the range of the candidate directions in which the robot can go across the obstacle point according to the included angles of the tangent lines and an X-axis, and getting the direction in which the robot can go across the obstacle point; defining a cost function to evaluate all feasible directions, and selecting the optimal direction of the next circle of motion of the robot; and working out the linear speed and angular speed of the robot by using a speed control policy. According to themethod, the robot can avoid an obstacle in an unknown environment, and has high performance; and without deeper theoretical foundation, the method is simple, smart, easy to understand and practical, requires small calculation, and is particularly suitable to use.