The invention relates to a PQF rapid online centering device and method. The device comprises an outlet positioning sleeve, an inlet positioning sleeve, a centering rod, hole type standard sample rings and an inlet positioning sleeve tile. The centering rod is sleeved with the multiple hole type standard sample rings in sequence and fixed by pins, one end of the centering rod is inserted on the outlet positioning sleeve, and the other end of the centering rod is placed on the inlet positioning sleeve and fixed together by a bolt through the inlet positioning sleeve tile. The device has the beneficial effects that centering adjustment can be carried out once by replacing a machine frame once, rapid online centering of a memorial gate and a hole type of the machine frame can be completed within 2 hours, it is ensured that the online rolling hole type center of each machine frame coincides with a rolling line, PQF continuous rolling wall thickness precision is ensured, and the problems ofcomplicated procedures, time and labor consumption, low centering precision and the like in the centering process of the PQF continuous rolling can be solved.