Smoking is often thought of only in terms of its impact on lung health. It is not known that cigarette smoke contains many chemical carcinogens and carcinogen precursors, which have been recognized as one of the major risk factors for many diseases and tumors, and have been widely confirmed in epidemiology, cytogenetics and molecular genetics. A great deal of research has also been carried out on the effects of smoking on reproductive function both at home and abroad. In this paper, we would like to summarize the effects of smoking on semen quality, testicular and epididymal damage, sex hormones and sexual function and their possible mechanisms. The effects of smoking on semen quality in men Semen quality is commonly measured by various indicators such as semen volume, semen pH, sperm density, sperm count, sperm forward motility, sperm survival and normal sperm morphology, etc. Kunzle et al. carried out a study on the relationship between smoking and semen quality in an infertile population, and the results showed that sperm density and normal sperm morphology in smokers were significantly lower than that in non-smokers. In a study of 655 smokers and 1,131 non-smokers, Kunzle et al. found that sperm density, total sperm count, and motile sperm count were significantly lower in smokers compared to non-smokers, with decreases of 15.3%, 17.5%, and 16.6%, respectively. Normal morphology sperm rate of smokers was 21.2%, compared with 23.7% of non-smokers, also decreased (P=0.0007); and sperm viability, semen volume, and fructose concentration of smokers were also slightly decreased, but did not reach statistically significant levels.Vine et al. conducted a meta-analysis of more than 20 papers, and the results showed that sperm density decreased by 13%-17%, but did not find any statistically significant differences. A meta-analysis of more than 20 papers by Vine et al. showed that compared with non-smokers, smokers had a 13%-17% decrease in sperm density, but no significant dose-effect relationship was found, while sperm motility decreased by about 20%. We randomly selected 110 smokers and 110 non-smokers in the preconception counseling group, the age of the subjects was 23-36 years old, and the subjects were in normal health, excluding those with oligospermia and azoospermia. The smoking group smoked for 2-15 years and 3-30 cigarettes/d; the non-smoking group never smoked. The results of semen examination showed that the normal morphology spermatozoa rate and the fast forward motility spermatozoa rate of the smoking group were significantly lower than those of the non-smoking group, and the sperm survival rate was also slightly lower than that of the non-smoking group. Semen volume and sperm density were not significantly different between the smoking and non-smoking groups. The results of Guan et al. also showed that there was a significant difference in sperm survival rate and sperm density between the smoking and non-smoking groups.