To provide an oil recovery method for a multi-type air conditioning system capable of efficiently and surely recovering refrigerating machine oil in system update, and to provide the multi-type air conditioning system.

A heat exchanger 200 sends a high-pressure refrigerant in a gas-liquid two-phase state, obtained from high-temperature, high-pressure overheating gas, into a high-pressure gas pipe 5 to flush away refrigerating oil, sticking on inner peripheral surfaces of a high-pressure gas pipe 5 and a low-pressure gas pipe 7 after the heat exchanger 200, together with the refrigerant. In an oil recovery tank 100, the refrigerating oil is recovered. Thus, the refrigerating oil is surely recovered from the high-pressure gas pipe 5 in which it was difficult before to recover the refrigerating oil since only the overheating gas flows.