| A life cycle inventory analysis model for all life stages of solar assisted straw biogas system is developed, including raw materials acquisition, construction, straw transportation, operation and maintenance, biogas using and eventually waste management. Based on on site investigation and measurement of a solar assisted straw biogas project, the life cycle fossil energy consumption and carbon emissions are calculated. The results show that the fossil energy consumption of the solar assisted biogas system is 0.173 MJ?MJ-1, and the carbon emission is 0.121kgCO2eq?MJ-1. When compared to natural gas, the fossil energy consumption of straw biogas is only 15.6% of the natural gas, the carbon emissions is 55% higher than that of the natural gas. The life cycle carbon emissions of solar assisted biogas system is 59.7% lower than straw burning.