A carbon fiber plate synthesis device includes an upper base and a lower base; the upper base is fixedly connected with the lower base; the lower base is provided with a rotary slot; the rotary slot is provided with a rotary table in an annular rotation manner; the rotary table is provided with a die body slot, an inverted pouring slot, a lower pressing slot and a conveying slot in a manner of spacing at 90 degrees, wherein the die body slot, the inverted pouring slot, the lower pressing slot and the conveying slot each have the beginning end outwards and communicate up and down; the left endof the rotary slot is provided with a communication slot communicating the outside and the conveying slot; a part, located below the conveying slot, in the lower base is provided with a mounting slothaving a beginning end facing to the left; the mounting slot is provided with a conveying device extending to the left; the center of the bottom wall of the rotary slot is fixedly provided with a motor; the motor is provided with a rotary rod; the rotary rod stretches into the rotary table and is fixedly connected with the rotary table; the upper base is provided with a mounting cavity, wherein the mounting cavity cooperates with the die body slot, stretches up and down and penetrates up and down.