Four main device models (evaporator, condenser, compressor and expansion valve) of the sewage-source heat pump were developed and coupled. The MATLAB software was used for this simulation, and the effects of fouling resistance, sewage flow and sewage inlet temperature on the heating performance of sewage-source heat pump were calculated respectively. The results revealed that while the fouling resistance changed from 0 to 1(m²·K)/kW, the heating capacity of the device was decreased from 353 kW to 301 kW, decreased by 14.8%. While the sewage inlet temperature increased from 8 to 20 ℃, the heating capacity of the device was increased from 320 kW to 423 kW, increased by 32.1%. While the sewage flow increased from 10 kg/s to 20 kg/s, the heating capacity of the device was increased from 339 kW to 364 kW. The COP of this heat pump changed from 3.6 to 4.8 in the process, which illustrated the good heating performance of the sewage source heat pump.