Abstract: Carbon emission from manure aerobic composting were calculated referring to guideline of emission factor method and life cycle assessment．Total emissions include direct emissions from composting microbial degradation activities, indirect emissions from upstream activities such as electricity consumption of processing equipment, emission reductions from downstream activities such as organic fertilizer as a substitute for chemical fertilizer and soil carbon binding after land application．Results showed that the project could dispose 420 t of raw materials per day and produce 20 t of organic fertilizer, which brought 19.26 t CO₂e direct emission from compost biodegradation, 17.84 t CO₂e indirect emission from electricity consumption, 0.87 t CO₂e of emission reduction as a substitute for chemical fertilizer, 113.4 t CO₂e carbon sequestration for land application．Within scope of whole life cycle, net carbon sink was 77.18 t CO₂e, which could achieve negative carbon emission and effectively enhance soil carbon sequestration capacity, providing a technical model for agricultural emission reduction．