<p>A variable area turbine includes a volute casing (1), wherein an actuating mechanism (15) is installed on the volute casing (1) and an annular gas channel (3) having a gas inlet (2) is arranged inside the volute casing (1). An intake area adjusting machine (17) is provided in the annular gas channel (3) and is transmittably connected to the actuating mechanism (15). The intake area adjusting machine (17) divides the channel (3) of the volute casing (1) from the inlet (2) to the 90° section into an upper and a lower channels with different flow capacity, and adjusts and controls the operations of the two different channels orderly so as to control the flow area of the channels, adjust the state of the gas entering the turbine and satisfy the boosting requirement of an engine under whole operation conditions. The actuating mechanism (15) can adjust the rotating angles of a movable straight plate (9) and a movable tongue-shape baffle (13) on the basis of the actual condition of the engine to vary a throat area and the gas channels so as to realize a good match between the turbocharger and the engine under the whole operation conditions.</p>
