The work aims to reduce the error between the diameter of the finished cigarette and the ideal cigarette to improve the rotation flexibility and locking reliability of the pipe-forming large platen regulating mechanism of the high-speed cigarette making machine. The working principles of large platen locking mechanism and cigarette diameter regulating mechanism were analyzed to study the large platen regulating mechanism and the rolling quality of cigarette. The pressing force of large platen was tested to get the working parameters of spring. The large platen regulating mechanism was optimized for reliable self-locking. Through measurement, the pressing force of the two large platens was 137 N and 147 N, respectively. The elastic force of the compression spring was greater than 209.8 N, which ensured non-separation of large platens and good rolling quality. The locking mechanism of the large platen realized good self-locking effect when the maximum length of the optimized connecting rod was in the range of [29.2 mm, 29.7 mm].The pressing force calculation of large platen and the optimization of self-locking mechanism can effectively improve the rolling efficiency of cigarette and ensure the production yield.