A fluidized bed reactor , comprising a reactor shell (1-1), a reaction zone, a coke control zone and a delivery pipe (1-3); wherein the reactor shell comprises a lower shell and an upper shell, the lower shell enclose the reaction zone, the delivery pipe is disposed above the reaction zone and in communication with the reaction zone, an outer periphery of the delivery pipe is provided with the upper shell, the upper shell and the delivery pipe enclose to form a cavity comprising the coke control zone; an upper part of the delivery pipe is provided with a gas outlet; the reaction zone comprises a reaction raw material inlet and a coke controlled catalyst inlet; the coke control zone comprises a catalyst inlet, a coke controlled catalyst outlet, a coke control gas outlet, and a coke control raw material inlet; the coke control zone is an annular cavity; there are n baffles (1-5) arranged in the coke control zone, and the n baffles divide the coke control zone into n sub-coke control zones which comprise a first sub-coke control zone, a second sub-coke control zone, and an nth sub-coke control zone; a cross section of the coke control zone is annular in shape, and a cross section of the sub-coke control zone is circular sector; at least one catalyst circulation hole is provided on each of n-1 baffles so that the catalyst flows in an annular shape in the coke control zone, wherein n is an integer; and the catalyst inlet is arranged in the first sub-coke control zone, the coke controlled catalyst outlet is arranged in the nth sub-coke control zone, and the coke control gas outlet is arranged between two adjacent baffles, the coke control gas outlet is connected to the delivery pipe by a coke control zone gas delivery pipe (1-6). wherein the reactor shell comprises a lower shell and an upper shell, the lower shell enclose the reaction zone, the delivery pipe is disposed above the reaction zone and in communication with the reaction zone, an outer periphery of the delivery pipe is provided with the upper shell, the upper shell and the delivery pipe enclose to form a cavity comprising the coke control zone; an upper part of the delivery pipe is provided with a gas outlet; the reaction zone comprises a reaction raw material inlet and a coke controlled catalyst inlet; the coke control zone comprises a catalyst inlet, a coke controlled catalyst outlet, a coke control gas outlet, and a coke control raw material inlet; the coke control zone is an annular cavity; there are n baffles (1-5) arranged in the coke control zone, and the n baffles divide the coke control zone into n sub-coke control zones which comprise a first sub-coke control zone, a second sub-coke control zone, and an nth sub-coke control zone; a cross section of the coke control zone is annular in shape, and a cross section of the sub-coke control zone is circular sector; at least one catalyst circulation hole is provided on each of n-1 baffles so that the catalyst flows in an annular shape in the coke control zone, wherein n is an integer; and the catalyst inlet is arranged in the first sub-coke control zone, the coke controlled catalyst outlet is arranged in the nth sub-coke control zone, and the coke control gas outlet is arranged between two adjacent baffles, the coke control gas outlet is connected to the delivery pipe by a coke control zone gas delivery pipe (1-6). <EOS>