Improved exploring origin of mixed dust source (IEOMDS) was proposed by using particle swarm optimization (PSO) to calculate the contributions of all dust instead of search solution space with intelligence (SSSI), which was first applied in the method of exploring origin of mixed dust source (EOMDS) in CMB model. After that, IEOMDS was tested in source apportionment of atmospheric particulates for a city, and compared its results with EOMDS. The results showed that the contribution rate of dust according to IEOMDS model was 28.01%, which was lower than 28.75% according to the original model, and the ratios of calculated data and measured data of receptor elements based on IEOMDS model were closer to 1, indicating that the results of IEOMDS model are more accurate and reasonable.