Abstract: At present, the problems of energy depletion and environmental pollution caused by non renewable energy such as oil and coal have seriously hindered the sustainable development of our society. Biomass energy is a reliable low-carbon alternative energy with renewable, clean and other characteristics. Therefore, the energy transformation to renewable energy is crucial to China's development. Research shows that China has rich biomass resources. For example, agricultural wastes can be used to produce biogas by anaerobic fermentation of agricultural wastes straw, which can reduce a lot of carbon emissions. Therefore, it is of great significance for China's development to make full and reasonable use of this resource. This paper discusses two types of biogas power generation technologies using straw as raw material, namely, traditional biogas direct combustion power generation technology and biogas fuel cell power generation technology. Based on life cycle assessment (LCA) and time value dynamic analysis method, the feasibility of two types of biogas power generation technologies is comprehensively evaluated from both environmental and economic aspects. The feasibility of this technology is compared with that of coal-fired power generation technology, and the feasibility of straw biogas power generation technology in both economic and environmental aspects is discussed. In the feasibility analysis of environmental benefits, three potential values of environmental impact categories are considered: global warming (GWP), environmental acidification (AP) and human toxicity (HTP). The environmental impact potential of the three power generation technologies is calculated according to the equivalence factor of each environmental category. After the environmental impact potentials are standardized, the total environmental impact loads of different environmental categories are obtained. The analysis of the total environmental impact is consistent with the judgment of the environmental benefits of the three power generation technologies. The economic feasibility analysis adopts the dynamic analysis method of time value, and selects the dynamic investment payback period, internal rate of return and net present value as the analysis indicators. According to literature review, find representative power plants, and calculate dynamic payback period, net present value and internal rate of return by referring to capital input and output data of power plants. According to the calculation results, the economic feasibility of different power generation technologies is comprehensively analyzed. The results show that the biogas fuel cell power generation technology is the best in terms of total environmental impact, and the total environmental impact load is 8.55×10-4, followed by biogas direct combustion power generation technology, with a total environmental impact load of 2.15×10-2。 Compared with coal-fired power generation technology (2.97×10-1), the emission reduction rate reached 99.71% and 92.76% respectively. In terms of economic benefits, when the dynamic payback period and NPV are taken as indicators, the payback period of the straw biogas direct fired power generation project is the shortest (12.03 years), the NPV in the operation period can reach 1 361 246 Yuan/MW, and the economic benefits are the best; The second is coal-fired power generation project (14.5 years), with a net present value of 423 933 Yuan/MW; The dynamic payback period of biogas fuel cell power generation project is more than 20 years, and there is no surplus during operation. Therefore, compared with biogas fuel cell power generation technology, biogas direct combustion power generation technology has more significant economic benefits. This shows that biogas direct fired power generation technology will remain one of the best power generation technologies to replace coal-fired power generation in the future.