Real option is a way to quantitative assessment of project active values during decision, which is an amendment to the traditional NPV economic assessment. This paper uses real option theory and way to analyze the real option in CBM project development stage and operation stage, determines that the gross value of this CBM project is the sum of cash flow NPV and active values. Binary tree option pricing is used to construct CBM project investment assessment and model based on real option. Combined with a case study on CBM to LNG project, NPV, delayed option based on real option, expansion option, and compound option are used to calculate the investment values of CBM project, with major parameters analyzing their sensibilities at the same time. Results show that the project value by real option is outstandingly higher than that by traditional ways, but the combined option can increase the project values. Subject asset values and option pricing largely impact the CBM option values.