In this paper, a redesign of an existing computer case is Proposed by applying some guide lines of assembly and disassembly which have positive effects on environment. Some problems such as Increase of number of disassembly and vibration, and unfittable difficulty in assembly and disassembly of coy-ers are recognized through analysis of geometrical structure in view of both assembly and disassembly. A solution of these problems is proposed by ideas of positive environmental influence through ease of assembly and disassembly. Design for Environment Software is used to evaluate both redesigned and existing products. Time of assembly and disassemb]y and MET-point are especially calculated by the software, and these data give us a good guide for analysis of ease of assembly, ease of disassembly and environmental influence in both products.