Abstract Construction investment is regarded as the leading cause in Real Estate industry for a long time. During the process, land development is an important factor for company's profitability. However, professions in this industry always rely on personal experience to estimate the land development potential. In most cases, owners or upper management are the ones to make the decision. Not only the decision conflict the open policy, it also lack of the base from lesson learns after the project wrap up. It limited the build up of experience with in companies. After interviewing industry experts, we found that the reasons people rely purely on experience among land estimate industry, besides the unique characteristic of land, accuracy and trust worthy of information, is limited to estimation during development; especially data of the direct cost, indirect cost, annual interest rate, and return ratio is missing the land estimation technical specification. Thus, people in current industry normally use personal experience or the reference material from government. Project budget in construction industry normally is pretty huge, management budget is occupied in a small percentage; thus, members normally do not want to spend time to analyze in detail in the beginning. This research base on documents and experts interview, it verifies and gather analysis of land development estimation. At the same time, it also gathers current ERP¡]Enterprise Resource Planing¡^ to get the real internal data. Using DSS system to assist members to process decision-making characteristics and What-If functions in which supports decision maker's decision. Utilize historical statistics and market fluctuation to process estimation and provide project data and comparison pie chart. This will provide the decision makers more effective comparison to different projects. Use land developing analysis estimate to establish an estimation structure and foundation for business to adjust accordingly when government regulation changes. An updated estimation way of Decision support system will provides an advanced tool for land developers. This will help decision makers in land development estimation to reduced the blind spots and mistake due to overly rely on personal experiences.