Vertical distributions of aerosol optical properties based on aircraft measurements over the Loess Plateau were measured for the first time during a summertime aircraft campaign, 2013 in Shanxi, China. Data from four flights were analyzed. The vertical distributions of aerosol optical properties including aerosol scattering coefficients (sigma(sc)), absorption coefficients (sigma(ab)), Angstrom exponent (alpha), single scattering albedo (omega), backscattering ratio (beta(sc)), aerosol mass scattering proficiency (Q(sc)) and aerosol surface scattering proficiency (Q'(sc)) were obtained. The mean statistical values of sigma(sc) were 77.45 Mm(-1) (at 450 nm), 50.72 Mm(-1) (at 550 nm), and 32.02 Mm(-1) (at 700 nm). The mean value of sigma(ab) was 7.62 Mm(-1) (at 550 nm). The mean values of alpha, beta(sc) and omega were 1.93, 0.15, and 0.91, respectively. Aerosol concentration decreased with altitude. Most effective diameters (ED) of aerosols were less than 0.8 mu m. The vertical profiles of sigma(sc), alpha, beta(sc), Q(sc) and Q'(sc) showed that the aerosol scattering properties at lower levels contributed the most to the total aerosol radiative forcing. Both alpha and beta(sc) had relatively large values, suggesting that most aerosols in the observational region were small particles. The mean values of sigma(sc), alpha, beta(sc), Q(sc), Q'(sc), sigma(ab) and omega at different height ranges showed that most of the parameters decreased with altitude. The forty-eight hour backward trajectories of air masses during the observation days indicated that the majority of aerosols in the lower level contributed the most to the total aerosol loading, and most of these particles originated from local or regional pollution emissions. (C) 2015 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.