The utility model discloses an alkylation reactor in order to solve the problems of the existing alkylation reactor that the reaction temperature is more difficultly controlled, and the heat exchange is not considered and the like. The alkylation reactor comprises a lower mixing chamber (6) and an upper reaction chamber (1), wherein an alkane feed pipe (4) and a liquid acid feed pipe (5) are respectively arranged at the bottom and the lower part of the mixing chamber, and an outlet nozzle (7) is formed in the top of the mixing chamber. A draft tube (9) is arranged in the reaction chamber, and the inside of the draft tube is a liquid rising zone; an annular space as a liquid backflow zone (3) is formed between the reaction chamber and the draft tube. The alkylation reactor is provided with an olefin feed pipe (8). A heat exchange tube bundle (10) and a deflection baffle (11) are arranged in the reaction chamber, and a liquid outlet pipe (2) is arranged at the top of the reaction chamber. The alkylation reactor provided by the utility model can be used for reacting alkane with low-carbon olefin to generate high octane alkylation oil under the action of a liquid acid catalyst.