The invention discloses a PCB automatic collecting and placing machine and a working method thereof. The machine comprises a mounting seat, supporting frames, rolling and conveying discs, a collectingand placing cabinet, a rotary disc, an air blowing frame, a transverse rail rod, a longitudinal rail rod and a grabbing and placing seat, wherein the supporting frames are arranged at the two ends ofthe mounting seat, and the rolling and conveying discs are horizontally arranged above the two supporting frames. The machine has the beneficial effects that a plurality of air blowing cylinders on the air blowing frame synchronously blow hot air to a board body, so that the drying performance of a PCB is guaranteed when the PCB is collected and placed, dust and impurities on the PCB are blown away, so that the tidiness of the PCB when the PCB is collected and placed is guaranteed, then a hydraulic pump II on the collecting and placing cabinet drives a rotary disc to move downwards into a receiving bucket through a hydraulic rod, after a mechanical arm clamps the PCB through clamping jaws, the hydraulic rod drives the rotary disc to rise, a third rolling wheel drives the mechanical arm toextend out of a movable groove, and place the PCB into a loading groove of a loading frame, so that the automatic collecting and placing of the PCB can be completed, the operation of the collecting and placing machine is more time-saving and labor-saving, and the work is more efficient.