Accurate age estimation of bloodstains can provide enormous forensic value. Visible reflectance spectroscopy technique combined with partial least squares (PLS) is applied to accurately estimate the age of bloodstains for forensic purposes. Genetic algorithm (GA) combined with PLS is used to select the most efficient spectral intervals. The genetic algorithm interval partial least squares (GA- iPLS) models built in the optimal intervals, present better predictive capability than full-spectrum PLS model. GA-iPLS can validly select desirable intervals and improve predictive ability. Considering the effect of the specificity of bloodstains on models, the GAiPLS models built in age period from 2.00 h to 48.00 h and in age period from 48.00 h and 1080.00 h are achieved with correlation coefficient (Rp) of 0.9949/0.9924, root-mean-square error of prediction (RMSEP) of 1.59 h/43.56 h , residual predictive deviation (RPD) of 10.32/8.4243 respectively, which can be used to accurately predict the age of bloodstains from 2.00 h to 1080.00 h instead of GA-iPLS model in 2.00~1080.00 h. The results demonstrate that visible reflectance spectroscopy combined with GA-iPLS will be a reliable tool to accurately estimate the age of bloodstains for forensic practical applications.