An alkylation reaction apparatus has n reactors. In the n reactors, there are m reactors including the first reactor that have three reaction zones as defined below. According to the flow direction order of alkylation reaction streams, the three reaction zones are an x reaction zone, a y reaction zone and a z reaction zone respectively; based on the mixing intensity, the mixing intensity of the y reaction zone>the mixing intensity of the x reaction zone>the mixing intensity of the z reaction zone, wherein n≥1 and n≥m. An alkylation reaction system includes the aforementioned alkylation reaction apparatus, and a liquid acid catalyzed alkylation reaction process by using the aforementioned alkylation reaction apparatus or the aforementioned alkylation reaction system.