The content of PC in lecithin was determined by dual wavelength thin-layer scanning chromatography with chloroform-methanol-water(65∶25∶4,V∶V∶V)as developing system,λ_S=235nm,λ_R=260nm as measurement and reference wavelength,zigzag scanning with dual wavelength and peak area as quantifying method.The average content of PC in flax lecithin is 62.4% with the average recovery of 99.6% and the RSD of 3.42%.This method is economical,available and reliable.