The angular light-scattering measurement (ALSM) method combined with an improved artificial bee colony algorithm is introduced to determine aerosol optical constants and aerosol size distribution (ASD) simultaneously.Meanwhile,an optimized selection principle of the ALSM signals based on the sensitivity analysis and principle component analysis (PCA)is proposed to improve the accuracy of the retrieval results.The sensitivity analysis of the ALSM signals to the optical constants or characteristic parameters in the ASD is studied first to find the optimized selection region of measurement angles.Then,the PCA is adopted to select the optimized measurement angles within the optimized selection region obtained by sensitivity analysis.The investigation reveals that,compared with random selection measurement angles,the optimized selection measurement angles can provide more useful measurement information to ensure the retrieval accuracy.Finally,the aerosol optical constants and the ASDs are reconstructed simultaneously.The results show that the retrieval accuracy of refractive indices is better than that of absorption indices,while the characteristic parameters in ASDs have similar retrieval accuracy.Moreover,the retrieval accuracy in studying L-N distribution is a little better than that in studying Gamma distribution for the difference of corresponding correlation coefficient matrixes of the ALSM signals.All the results confirm that the proposed technique is an effective and reliable technique in estimating the aerosol optical constants and ASD simultaneously.