The present invention relates to a device of changing the gas flow pattern in the process chamber and a wafer processing method and system; a gas introduced from the gas inlet to the process chamber will process the wafer in the process chamber; a gas center ring is set in the process chamber to adjust the gas flow pattern, which includes a fixed component under the gas inlet and above the wafer, and a movable ring could locate in the first position or the second position respectively; when the movable ring is in the first position, the gas is delivered downwards to the wafer via the first opening set on the fixed component; when the movable ring is in the second position, the gas is delivered downwards to the wafer via the second opening set on the movable ring. The present invention constitutes the gas center ring by different combinations of fixed component and movable component, to change the gas flow pattern in the process chamber, achieving effective control on the wafer processing effects and to dispense with opening the process chamber during the adjustment process of gas center ring.