The aim of this study was to establish a novel method for isolating and purifying Leydig cells from mice testes. Testes of postpuberal mice were harvested and digested in a low concentration of collagenase NB4 for 15 min 2 times. Cells obtained were cultured in low glucose DMEM with 10% FBS. Immunofluorescence was used to detect the expression of Leydig cell biomarkers including 3β-hydroxysteroid dehydrogenase, cholesterol side-chain cleaving enzyme (CYP11A1) and 17α-hydroxylase/17,20-lyase (CYP17A1). It was found that the purity of the isolated Leydig cells was 69.6 ± 4.16%. After 7 days in primary culture, it increased to 90%. The testosterone synthase spectrum could be detected at the primary culture. In conclusion, the application of a low concentration of collagenase for differential digestion allows isolation of large quantities of viable Leydig cells.