At present the cigarette weight control system of high-speed cigarette machine is mainly used the techology of nuclear scanning for cigarette weight testing or feedback at home and abroad. The scanning head is used by radioactive material, so there is always exiting the danger of radiation to operators in actual operation system. In addition, recessive instability also existed in the control system. With the microwave detection technology, the energy parameter change caused by cigarettes in the microwave electromagnetic field was used to detect cavity density and moisture content of the tobacco rod. The weight and moisture content of the tobacco rod was detected and the cigarette weight was then controlled. The experimental results demonstrated the effectiveness and feasibility of the algorithm.