The present disclosure provides a laser speed measuring method, control device and a laser velocimeter, and relates to the technical field of security inspection. The laser speed measuring method comprises the steps of: acquiring detection data within a predetermined detection angle range in a plurality of paralleled horizontal planes having different heights, from a plurality of laser rays detected towards a road extending direction in the horizontal plane; acquiring three-dimensional point cloud data according to the detection data; determining a position of a measured object in the road extending direction according to the three-dimensional point cloud data; and determining a speed of the measured object according to the position change of the measured object along the road extending direction at different timing.