Abstract: For stabilizing and improving the quality of primary processing, SPC (statistical process control)was used to evaluate key parameters in primary processing, the process steps of ordering, casing, cut rag blending and flavoring were evaluated and improved. After then, the quality audit system was further improved by SPC. The results of improvement showed that: 1)the process capability index, PPK, of key parameters in primary processing increased by 0.23, the standard deviation of tobacco casing decreased by 56.5%, and the uniformity of cut stem blending increased from 94.27% to 97.38%; 2)the intra- and inter-batch fluctuations of sensory quality scores of cigarette samples reduced by 0.29 and 0.27, respectively, it indicated that the intrinsic quality became stabler; 3)the average PPK value of 5 indexes (hot air temperature in ordering cylinder, throughput of casing cylinder, casing ratio, hot air temperature in tobacco dryer, instantaneous flavoring ratio)increased by 6.1%.