The carbon emission during sewage sludge treatment is an important source of greenhouse gas. For the carbon reduction, the emissions from common treatment technologies are calculated with the mass balance model, then their lowcarbon degrees are evaluated, and finally the lowcarbon treatment strategies are put forward for different requirements. The results show that the technologies, such as digestion for methane recovery, incineration or coincineration for power production after drying with industrial waste heat, are the ones with the lowest carbon emission. Their lowcarbon degrees are 89.6%, 80.3% and 76.6% respectively. In the area where the above technologies cannot be applied, aerobic composting or landfill with aerobic stabilization pretreatment are the effective methods to reduce carbon emission. The lowcarbon treatment strategy, a new part of sludge treatment strategies, should be applied combining the local economy, technology and social conditions, so that it can meet the different requirements from sanitation to carbon emission reduction.