The work aims to solve the inefficiency and high cost of manual packaging in the production process of soft box hardening product of "Yuxi Jingjie" in prefabricated carton. Through structure analysis and improvement on YB65 carton packaging machine, only the 25-row cigarette bag pushing device of the original machine was retained. The prefabricated carton feeding and side cover opening device, the cigarette bag pushing device and the prefabricated carton output device were redesigned. The prefabricated carton filling technology changed the original carton paper forming process, and adjusted the equipment layout and phase of YB65 carton packaging machine and YB95 carton transparent paper packaging machine, thus realizing the packaging process of side-open prefabricated carton cigarette. Taking "Yuxi Jingjie" in Zhongzhi as the test object, the online running speed of filling equipment reached 25 cartons/min, the equipment efficiency reached 75.4%, the rejection rate of waste was 0.84%, and the efficiency of was increased by 19.3 times compared with manual filling. After putting the equipment into service, the fully automatic production of side-open prefabricated carton cigarettes is realized. The equipment runs stably and reliably, and the efficiency is improved significantly.