The particularity of the assembly and rectification processing of line-replaceable unit (LRU) in large-scale superpower laser facility is analyzed. Oriented bounding box (OBB) of down-load system， which is based on space region partition， is set up， and Minkowski sum is introduced into OBB calculation. Then the separating axis theorem is optimized， and a dynamic OBB hierarchy tree detecting method is created by combining locality principle of collision. The results from the assembly and rectification practice in a large-scale superpower laser facility confirm that the method is highly efficient and reliable.