An approach for genotyping of STR locus based on ultraviolet(UV) spectroscopy and support vector machine(SVM) was studied.Taking three different genotypes 10-10,11-13 and 13-13 of locus D5S818 as example,the conditions for PCR amplification and UV spectral detection on a DNA fragment containing the polymorphism sites were optimized.Under the optimal conditions,the ultraviolet spectra for the samples were obtained.Using these spectra as identifying variables,the SVM model of the three genotypes was established to overcome effectively the spectral colinearity,and a right prediction rate of 100% was obtained.The proposed method was simple,rapid and low cost,and could be indirectly used to determine the three genotypes of D5S818 locus based on PCR amplification and UV spectra of the samples without any pretreatment.