随着我国天然气需求量的日益增加，煤层气作为煤矿伴生的非常规天然气资源，发展越来越受到关注。虽然有着巨大的市场前景，但工程投资规模大,建设成本管理难度较大,也为该类工程项目建设的管理提出新挑战。X煤层气项目是我国建设最成功的煤层气建设项目之一。该项目采用全过程的成本管理模式，明确了建设阶段和竣工验收阶段的控制目标，基本实现了成本的有效控制。但通过整个项目的成本管理及预算执行情况分析，对比项目估算、概算、预算与实际成本产生的差异，我们发现该项目忽视了决策和设计阶段的成本管理，这使得项目在建设阶段没有详实的控制依据，造成建设阶段成本管理难度加大。虽然建设和竣工验收阶段采取了一系列成本管理措施，但最终效果并不理想。结合其他项目成本管理的经验以及相关理论，本文认为决策阶段和设计阶段是煤层气项目成本管理的关键阶段。基于X煤层气项目的研究，本文针对煤层气项目成本管理关键阶段，即决策阶段和设计阶段展开研究，通过项目成本管理流程、目标、作用及影响因素分析，提出在煤层气项目决策阶段，根据工作流程，可使用生产能力指数法、格朗系数法、指标估算法和投资分类估算法进行投资估算，逐步做实投资估算，为决策者提供合理、有效的决策依据；在设计阶段推行设计招标、限额设计、标准化设计等方法，并运用价值工程理论，对设计方案进行优化、比选，最终优选确定出最佳方案，努力实现项目效益的最大化。本文的研究，采用理论和实践相结合的论证方法，通过实际项目案例，提出煤层气项目成本管理建议，对未来煤层气项目的成本管理具有很好的指导意义。

With the increasing demand of natural gas, the development of coal bed methane(CBM), a kind of unconventional gas resources associated with coal mine, has attracted more and more attention. Although there is a promising market, large-scale investment demand and difficulty of construction cost management restrict the development of CBM industry. The Project X, one of the most successful CBM projects in China, uses cost management method to achieve an effective cost control with clearing each target in construction phase and completion acceptance phase. However, by analyzing cost management and budget execution of this project and comparing the differences among estimation, budgetary and actual cost, we found that this project has not performed cost management in decision-making phase and design phase, which resulted in much difficult in construction phrase. Even though lots of cost management measures are adopted in construction phase and completion acceptance phase, the cost of this project is still too large. Therefore, cost management in decision-making phase and design phase is one of the most important stages for CBM project.This paper focuses on the cost management in decision-making phase and design phase. Analyzing process, target, effect and influencing factors of cost management in those two phrases, we concludes that production capacity index approach, the Grand coefficient method, index evaluation method and investment evaluation classification method can be used in decision-making phase and quota design, standardized design and value engineering theory can be used in design phase. Based on those measures, it is possible to choose a best optimum scheme for a CBM project to get maximum benefit.The paper is significant for the theory and practice of the construction cost management in CBM project.