The invention relates to an automatic control system and method for cigarette rod weight. The automatic control system comprises an MC2 cigarette rod physical detector, a cigarette rod weight index acquiring device, an cigarette machine electric control system, a correlative factor acquiring device, an application server, a real time history/relational database, a data analyzing server, an onsite operation terminal, a correlative factor control server and an industrial Ethernet. The real time history/relational database consists of a real time history database and a relational database. According to the invention, a set of a complete closed loop system featuring functions of acquiring and controlling is provided to genuinely realize smart control on cigarette rod weight.