The circumference error of the cigarette products for filter rod and cigarette will directly affect the quality of the connection of cigarette and raw materials consumption, and so the circumference of filter rod and cigarette is an important item that must be measured and controlled. At present, the main method of measuring filter rods and cigarettes circumference is the laser method. In this thesis, the laser method measuring the principle and process is described, and the analysis is done in five aspects: the position relationship between the calibration standard and the laser beam scanning plane, the position relationship between the sample and the laser beam scanning plane, penetration of laser light through the sample, the roundness of samples, and the cleanliness of each optical device at the laser transmission path. The corresponding solutions are provided.