The invention provides a tower crane anti-collision method and system. The method comprises the following steps: image information and moving information of target objects are acquired; whether the target objects are moving target objects or static target objects is judged; if the target objects are moving target objects, target object background frames and adjacent background frames are established according to movement information, the target object background frames and the adjacent background frames are spliced, motion track prediction is carried out, so that a two-dimensional moving track prediction is obtained; the moving target objects are tracked by utilizing rays reflected by the laser incident moving target objects to obtain a three-dimensional moving track prediction; if the target objects are the static target objects, the static target objects are positioned according to the image information, and geometric coordinates and object distances are calculated according to the positioning result; and whether the object distances meet a safety threshold value or not is judged, and an alarm control program is started under the condition that the safety threshold value is not met. The problem of the collision between hoisted objects and fixed or moving obstacles can be solved through a pattern recognition technology, and therefore green assembly type construction engineering is realized.