Abstract：L-phenylalanine CSP was prepared by L-phenylalanine and stearoyl chloride via esterification, amidation, saponification and acid chloride reaction, The CSP had been characterized by FT-IR ,1HNMR spectra and elemental analysis. According to the mass ratio of 3:1, The CSP and silica gel were used as thin layer chromatography，V（ethanol）: V（ethyl acetate）: V（triethylamine）=11:5:1 as development system, duloxetine was separated on the TLC,(R-)duloxetine Rf1=0.87,(S-)duloxetine Rf2=0.75.