Objective To explore the effect and heaviness of smoking on the routine parameters of semen quality.Methods A total of 727 eligible subjects including 421 smokers and 306 nonsmokers were selected in 2004-2006 in Hebei,Shanxi,Guizhou,Zhejiang and Shandong provinces.Data on background information,general demographic characteristics,exposure to smoking and related confounding factors were obtained through a questionnaire survey.Semen samples of all the subjects were collected during the period of study.Parameters of semen were examined according to the manual recommended by WHO.Results Four models from the multiple logistic regression regarding the semen routine parameters were used as the dependent variables to be fitted in descending order respectively,while six confounders including area,age,abstinence time,education level,history of alcohol intake and the exposure to pesticides atc.,were adjusted.Results showed that smoking could affect the sperm viability,with significantly higher proportion of abnormal sperm viability seen in the smoking group (OR= 1.77,95％ CI:1.12-2.80).Proportions regarding the abnormal mobility and morphology of sperms in the smoking group were also significantly higher than in the control group,with OR values as 1.51 (95％CI:1.00-2.27) and 2.55 (95％CI:1.68-3.88) respectively.The density of sperms was significantly decreased in the smoking groups who smoked more than 20 cigarettes per day (OR= 1.70,95％CI:1.05-2.76) or the total numbers of cigarette consumption exceeding 150 000(OR=1.84,95％CI:1.03-3.29).Conclusion Smoking showed adverse effects on the quality of semens,especially for heavy or long-term smokers.