Abstract This design is take yearly produces 740,000 tons styrene as the production goal, after uses the benzene alkylate production ethyl benzene to catalyte the dehydrogenationsystem to result in the styrene the technique.The system takes the ethyl benzene installment technical process mainly to divide into the alkylate and the selective evaporation two stages and the styrene model installment technical process mainly divides into the dehydrogenation and the selective evaporation two construction sections.dehydrogenation section consists of three parts, including ethyl-benzene dehydrogenation reaction:craft, evaporate steam condensate liquids treatment and tail gas compression titus absorption. Distillation sections is made up of four parts, ethyl benzene a styrene separation, syrene distillation, ethylbenzene recovery, benzene, toluene separation. This design of styrene distillation unit adopts sequence separation process, namely coarse styrene fluid first flowing to benzene, toluene tower, then separate light component benzene, toluene, etc and separation ethylbenzene and styrene. According to relevant design requirements for the whole production section process design and selection of equipment scientifically. This article mainly aims at the process of distillation unit materials calculation, heat calculation, to calculate the minimum reflux ratio and appropriate reflux ratio etc to determine the actual tower number plates and actually feeding position. Through the column of ethyl-benzene - styrene, tower diameter and high tower, column top condenser, transformation reboiler tower kettle such ancillary equipment and related fitting for size calculation and selection. Key words:Styrene distillation progressive separation process design