After China's entry into WTO, some well-rounded foreign real estate agencies and home financial company have entered into China's real estate market. Encountered with gradually matured market, the real estate enterprises pay more attention to the issue of how to preserve the biggest profit space. In this paper, the cost management will be investigated deeply and related measures will be put forward. This paper follows the principle of standing out the emphasis and exploring deeply the essential problem. With the theory-coupled-examples method, the fundamentality of cost management in decision-making and programming design stage is studied. The object system method is used to evaluate the quality of the decision-making and using compound engineering designing principle to manage the cost. The results prove that the decision-making as well as programming design stage is the key of cost management, which should be taken seriously by China's real estate enterprises.