To simultaneously determine the three-component system of isobutanol, isoamyl alcohol and n-propanol with overlapping spectra.Methods Experimental conditions were optimized according to the characteristics of color reaction of alcohols with paradimethylaminobenzaldehyde, and partial least squares (PLS) was use to simultaneously determine isobutanol, isoamyl alcohol and n-propanol with serious spectrum overlapping. Results The recoveries of simulative mixed samples were 99.8%, 99.6% and 99.9% with RPEs 0.88%, 1.81% and 0.90%, respectively. Recoveries and RPEs were within the allowable range. Conclusion Partial least squares method for the determination of three-component system of isobutanol, isoamyl alcohol and n-propanol was stable and reliable.