Physicochemical and biological properties were studied during the forced aeration composting of digested sludge and sawdust under ambient temperature between 9 and 15°C. The temperature above 55°C in the core of composting pile kept for 5d during the whole composting process. Total organic carbon and moisture content obviously declined with the increase of composting time, and the content of NO3--N increased. pH, electrical conductivity, NH4+-N, cellulose and urease activities originally increased and then declined. The germination index was 82.82% on day 35. The research results showed that forced aeration composting of digested sludge and sawdust under low ambient temperature could meet the demand of mature on day 35.