In order to realize the lightweight of the rear seat back panel, under the premise of meeting the performance and assembly requirements of the carbon fiber seat back, the seat back panel was redesigned to minimize the mass of the seat back panel while meeting the requirements of safety performance. The finite element analysis software was used to establish the finite element model of the rear seat of automobile, and the Optistruct software was used to optimize the lightweight design of the carbon fiber reinforced plastic rear seat. Finally, the carbon fiber backrest of the car seat has a mass of 1.579kg and meets the design purpose and requirements of the rear seat.