Cigarette circumference was solved with image processing method by using LabVIEW as software platform and CCD as image collection of cigarette circumference. The composition of the detection system was introduced. Collected cross-sectional image of cigarette was processed with gray-scale transformation, median filtering, threshold segmentation, morphological opening operation and other image processing algorithms to calculate the circumference of cigarettes. Pixel value of cigarette circumference was calculated by LabVIEW software. Cigarette circumference was corrected by mathematical optimization with least squares method. Simulation results showed that the detection accuracy was 94.36%; the method can accurately detect the length of cigarette circumference, which is helpful for improving the quality of cigarette products.