The utility model discloses an alkylation reactor for generating high-octane rating alkylate oil. The reactor is a cylindrical tank body with round tops at the two ends; the middle part of the tank body is of a tube nest structure and consists of a tube pass and a shell pass, wherein the tube pass is a reaction area, and the shell pass is a heat exchange area; a pre-distribution area and a reactant outflow area are formed at the two ends of the tank body respectively; the two ends of the tank body and the middle cylindrical part are separated by two porous baffles; and the porous baffles communicate the two ends of the tank body and the tube pass of the middle cylindrical part and separate the two ends from the shell pass so as to sequentially communicate the pre-distribution area, the reaction area and the reaction outflow area and separate the three areas from the heat exchange area. The alkylation reactor disclosed by the utility model is applicable to a reaction for generating high-octane rating alkylate oil from isoalkane and low-carbon alkene under the effect of a liquid acid catalyst, and has the characteristics of skilful structure, good reaction effect, high operation elasticity and the like.