The invention relates to a gas and steam combined cycle unit steam extraction integrated heating system and an operation method thereof, and belongs to the technical field of combined heat and power generation. The gas and steam combined cycle unit steam extraction integrated heating system comprises a gas turbine set and a steam turbine set, wherein the gas turbine set comprises a gas turbine compressor, a gas turbine combustion chamber, a gas turbine and a first power generator, and the steam turbine set comprises an exhaust-heat boiler, a steam turbine high-pressure cylinder, a steam turbine intermediate-pressure cylinder, a steam turbine low-pressure cylinder, a second power generator, a condenser, a condensation water pump, a gland heater, a deaerator, a first temperature reduction and pressure reduction device, a second temperature reduction and pressure reduction device, a third temperature reduction and pressure reduction device, acting equipment, power equipment, a heater fora heating network, a drainage heat exchanger and a circulating pump for the heating network. According to the gas and steam combined cycle unit steam extraction integrated heating system and the operation method thereof, on the basis of an energy gradient utilization principle, integrated design of different steam extraction modes is performed, so that the thermoelectric decoupling operation capability of the combined cycle unit is effectively improved, and the heating requirements of residents are guaranteed.