Precision of filter rod circumference is an important performance index of the cigarette manufacturing. The forming mechanism of filter rod, equipment vibration and other interference factors all lead to fluctuations of precision of filter rod circumference which can affect the precision of the cigarette. The existing KDF2/3 filter rod making machine which has the characteristics of compact structure (small space dimension), high speed (300 m/min) and discrete control of precision of filter rod circumference is the core equipment of filter rod production. This paper puts forward four kinds of online real-time detection schemes on precision of filter rod circumference which are Aomeijia’s many groups of detectors scheme, Keyence’s contour detection scheme, high precision measuring diameter instrument detection scheme using multiple sets of KD series meter and the 360 degrees rotating survey meter. On the basis of extensive analysis and experimental validation, Aomeijia’s four-way diameter measuring instrument scheme is optimal. The scheme applies laser to non-contact high speed scan on key radial diameter size of filter rod which achieves 0.001mm high precision detection.