Engineering plastic is used as a replacement for metal structural parts, in particular in the automotive industry, aiming at its lightweight effect that leads to the reduction of carbon dioxide emission. Design of the engineering plastic parts requires a broad range of expertise, which are unable to be covered by one company. For effective product design, activities and information related to the design should be arranged across the related companies such that required qualities can be designed systematically. Such companies appear to be well collaborated; however, their design work is actually separated on company basis. Although the computer aided engineering (CAE) environment is applied to processes of the design, the CAE environment is not utilized properly, which does not contribute to optimizing the processes. In order to optimize the processes with utilizing the CAE environment, the processes need to be organized so as to provide design-related information for each design activity by clarifying requirements and specifications of the activities. In this paper, we proposed a consistent business process model of the engineering plastic parts design with a template that has structured PDCA (Plan, Do, Check, Action) cycles for clearly defining activities related to the processes. Then, the current process of product design (“As-Is”) was analyzed by the consistent business process model (“To-Be”). As a result, the root cause of the current process was identified to inconsistent engineering standards that are used in CAE simulations. Finally, two countermeasures to overcome the company-based unfavorable structure were proposed for utilizing the CAE environment in the design process, which leads to systematizing the design process.