Abstract: A computer-aided piping system has been researched and established for complex 3D plumbing system on aircraft engine.This system is based on the user-defined pipe object and realizes piping on aircraft engine casing with same or different geometry.The system also provides the ability of editing the pipe's property and shape and ability of interference and clearance checking.The piping object is capable of intelligent response to the change of the joint.The system can also serve as a piping system of automobile,or for petroleum and chemical field.