The invention discloses a leaf tobacco processing method capable of selectively reducing a release amount of NNK (Nitrosamine) in cigarette smoke. The leaf tobacco processing method comprises the steps of: firstly, preheating wet leaf barrel, and charging when circulatory hot wind is at 80 DEG C to 120 DEG C; then adjusting a hot steam valve and a wet steam valve based on the positions of the processed leaf tobacco, and respectively controlling a temperature and a moisture content of the wet leaf tobacco; and finally, processing by adopting full steam at a temperature which is accordance with the technical requirements of YC/T146-2010 Leaf Tobacco Threshing and Redrying Process Specification. The method has obvious effects of selectively reducing the release amount of the NNK in the cigarette smoke, achieves the reduction amplitude of 11.20-38.21%, has good repeatability, is applicable to the practical threshing and redrying production, expands the leaf tobacco processing technology of reducing harmful components in the cigarette smoke, and has relatively good practical significance and reference function for harm reduction and tar reduction in the industry.