The invention discloses a boxing machine paper box opening method. A rotary table is driven through a servo motor, a cam plate is provided with double cam grooves including the outer cam groove and the inner cam groove, the outer cam groove is used for controlling operation actions of a suction nozzle of a box opening rod assembly, the inner cam groove is used for controlling operation actions of a suction nozzle of a box taking rod assembly, then box absorbing and box placing actions of the box taking rod assembly can be finished, and the paper box opening function is finished through the box opening rod assembly. The invention further discloses a paper box opening mechanism. The paper box opening mechanism comprises a rotary table assembly, a servo motor assembly, the box opening rod assembly with the suction nozzle, a box opening driving tooth block assembly, the box taking rod assembly with the suction nozzle and a box taking driving tooth block assembly. According to the boxing machine paper box opening method and the paper box opening mechanism, working is reliable, cost can be effectively reduced, a paper box can be opened more reliably, the running speed is high, the paper box opening mechanism is simple in structure, and the working control process is simple.