Along with the development of the measuring technique and computer technology, market competition is aggravating, the modern product of the design cycle demands shorter especially in automobile field. In order to meet the development requirements of automobile, we must reduce the design cycle and cost, so the Reverse Engineering (RE) technique has applications widely. This paper describes some concepts about reverse engineering. It points out the key technologies in reverse engineering like cloud data processing technology and surface reconstruction technology. Finally this paper uses the reverse engineering software CATIA to recover one inner automobile panel and describes the process of reverse engineering in details to build 3D model.