Abstract: Disclosed in the present disclosure is a method for preparing (S)-1,2,3,4-tetrahydroisoquinoline-1-carboxylic acid and derivatives thereof, comprising: taking a racemate of a compound represented by Formula (I) or a racemate of a salt of the compound represented by Formula (I) as a substrate, and making a R-isomer of the compound represented by Formula (I) in the substrate react under the catalysis of oxidative dehydrogenase to generate imino acid represented by formula (II); and converting the imino acid represented by Formula (II) into an S-isomer of the compound represented by Formula (I) in the presence of pipecolic acid reductase and a coenzyme capable of supplying hydrogen anions. The present disclosure is featured by mild reaction condition, strong stereoselectivity, high reaction efficiency, high conversion rate, etc.