Reverse engineering has been widely used to analyze existing objects such as software systems, products, etc. The main purpose is obtaining information by disassembling a product and finding an improved design. Based on the disassembling work, research for a systematic analysis has been well developed, but reverse engineering has been rarely employed in finding a new (an improved) design of a complex and large scale product. Therefore, even though the ultimate goal of reverse engineering is an improved design (or redesign), the opportunity to make a new feature is rarely given. A novel method of reverse engineering is proposed by using the axiomatic design viewpoint. The method not only keeps the fundamental concept of reverse engineering, but also realizes a new (or improved) design according to proposed procedures such as inference, design improvement module and a qualitative evaluation. A complex and large scale product (a ceiling type air conditioning system) is chosen as a case study to validate the proposed method. As a result, useful information for a new (or improved) design is obtained and also a new part (filter cleaning system) is proposed. The methodology provides a good way to design a new (or improved) product.