An outdoor unit (100) for a heat recovery VRF air conditioning system and a heat recovery VRF air conditioning system are provided. The outdoor unit (100) comprises: a compressor (2), having an exhaust port (a) and a gas return port (b); a reversing assembly (3), having a first valve port (c), a second valve port (d), a third valve port (e) and a fourth valve port (f); an outdoor heat exchanger (4), having a first end connected to the first valve port (f), and a second end connected to the second connector (12); a plurality of one-way valves, wherein each one-way valve has a circulation end and a stop end, and each one-way valve is opened only in one direction from the circulation end to the stop end; a throttling element (6); and a gas-liquid separator (9).