Abstract: The effects of environment humidity on physical and chemical characteristics and smoking quality of cigarette were studied under given temperature(22℃),the relationships between the changes of free nicotine,nicotine and pH values of cigarette smoke and its smoking quality were emphatically analyzed.The results showed that:1) environment humidity was positively correlated with cigarette weight and draw resistance;2) under the circumstances where air humidity was low,the contents of moisture,nicotine and tar in smoke decreased,while the ratio of tar/nicotine increased;under the circumstances where air humidity was high,the contents of moisture,tar and the ratio of tar/nicotine in smoke increased,while nicotine reduced evidently;3) environment humidity obviously affected cigarette smoking quality,and the ratio of free nicotine to nicotine significantly positively correlated with taste concentration and satisfaction.Under a circumstance of low air humidity,the lower the ratio of free nicotine to nicotine was,the higher the irritation of cigarette smoke would be.