A preparation method of S-nicotine, characterized by comprising the following steps: S1: adding nicotinate and γ-butyrolactone into an organic solvent I, performing condensation in the presence of a base catalyst to obtain a condensation product, and performing cyclization on the condensation product in the presence of hydrochloric acid to obtain 4-chloro-1-(3-pyridin)-1-butanone; S2: reacting the 4-chloro-1-(3-pyridin)-1-butanone with an amination reagent under alkaline conditions to obtain 4-amino-1-(3-pyridin)-1-butanone; S3: adding the 4-amino-1-(3-pyridin)-1-butanone and (+)-B-diisopinocampheyl chloroborane into an organic solvent II, and reacting at -30 to 10°C to obtain -4-amino-1-(pyridin-3-yl)butan-1-ol; S4: reacting the -4-amino-1-(pyridin-3-yl)butan-1-ol with a chlorination reagent to obtain -4-amino-1-(pyridin-3-yl)butyl-1-chlorine; S5: performing cyclization on the -4-amino-1-(pyridin-3-yl)butyl-1-chlorine in the presence of a base to obtain S-demethylnicotine; and S6: reacting the S-demethylnicotine with an amine methylation reagent to obtain crude S-nicotine, and purifying to obtain S-nicotine; wherein at S1, the base catalyst is selected from one or more of alkali metal alkoxide, alkaline earth metal hydride, alkaline earth metal oxide, amine, a metal salt of amine, hydroxide, carbonate, and bicarbonate; at S3, the organic solvent II is selected from one or more of tetrahydrofuran, dimethyl tetrahydrofuran, and 1,4-dioxane; at S4, the chlorination reagent is oxalyl chloride; and a molar ratio of the -4-amino-1-(pyridin-3-yl)butan-1-ol to the oxaloyl chloride is 1:; and at S2, a molar ratio of the 4-chloro-1-(3-pyridin)-1-butanone to the amination reagent is 1:. S1: adding nicotinate and γ-butyrolactone into an organic solvent I, performing condensation in the presence of a base catalyst to obtain a condensation product, and performing cyclization on the condensation product in the presence of hydrochloric acid to obtain 4-chloro-1-(3-pyridin)-1-butanone; S2: reacting the 4-chloro-1-(3-pyridin)-1-butanone with an amination reagent under alkaline conditions to obtain 4-amino-1-(3-pyridin)-1-butanone; S3: adding the 4-amino-1-(3-pyridin)-1-butanone and (+)-B-diisopinocampheyl chloroborane into an organic solvent II, and reacting at -30 to 10°C to obtain -4-amino-1-(pyridin-3-yl)butan-1-ol; S4: reacting the -4-amino-1-(pyridin-3-yl)butan-1-ol with a chlorination reagent to obtain -4-amino-1-(pyridin-3-yl)butyl-1-chlorine; S5: performing cyclization on the -4-amino-1-(pyridin-3-yl)butyl-1-chlorine in the presence of a base to obtain S-demethylnicotine; and S6: reacting the S-demethylnicotine with an amine methylation reagent to obtain crude S-nicotine, and purifying to obtain S-nicotine; wherein at S1, the base catalyst is selected from one or more of alkali metal alkoxide, alkaline earth metal hydride, alkaline earth metal oxide, amine, a metal salt of amine, hydroxide, carbonate, and bicarbonate; at S3, the organic solvent II is selected from one or more of tetrahydrofuran, dimethyl tetrahydrofuran, and 1,4-dioxane; at S4, the chlorination reagent is oxalyl chloride; and a molar ratio of the -4-amino-1-(pyridin-3-yl)butan-1-ol to the oxaloyl chloride is 1:; and at S2, a molar ratio of the 4-chloro-1-(3-pyridin)-1-butanone to the amination reagent is 1:.