Through analysis of basic assumptions and limitations of the conventional real estate investment decision method, in this paper, its unconformity to the investment environment, which includes a great number of uncertain elements, is pointed out. By analyzing the real option and the price formula, the pattern of real option in real estate investment decision is put forward and this breaks through the limitations of the conventional investment decision method and makes the decision scientifically and reasonably, moreover, it has some directive significance to investment administration work of real estate corporation.