Abstract: In order to evaluate the accuracy of flavor application in filter rod making and the process capability index of the equipments for making the same,the contents of ethanol,1,2-propylene glycol and glycerol in 16 samples of common liquid cigarette flavors and 10 samples of liquid filter flavors were determined.The XR control chart of 1,2-propylene glycol content in filter rod and process capability index (C _pk) of filter rod makers No.1 and No.2 were studied by using 1,2-propylene glycol as a marker.The results showed that:1) Ethanol was found with the highest contents in all the 26 samples,1,2-propylene glycol found in 25 samples.Glycerol was not detectable in 14 samples,including the 10 samples of filter flavors.2) The average recovery of 1,2-propylene glycol in filter was 99.95% with the RSDs of 1.41% and the limit of detection of 0.045 mg per filter rod.3) The filter rod makers No.1 and No.2 were in stable controlled state.4) The C _pk of filter rod makers No.1 and No.2 was 1.46 and 0.97,respectively.It was concluded that the flavoring accuracy of filter rod and the C _pk of filter rod maker could be evaluated by using 1,2-propylene glycol as a marker.