A remote measurement method for the mass concentration of fugitive-dust-emission particulate based on backward light scattering is proposed to overcome the problem that there is no effective measurement method for the mass concentration of particulates from open and fugitive-dust-emission sources such as construction sites. The measurement result of the proposed method is the average mass concentration of particulates of the cylindrical beam segment. The established theoretical model takes into account the backscattered light energy, mass concentration of particulates, and measuring distance. A portable measuring device is developed using a semiconductor laser as a light source and complementary metal oxide semiconductor image sensor as a detector, as well as an image processing program. The linear relationship between the mass concentration of particulates and output value of the system is verified by calibration experiments, which renders the calibration curve. Effects of large particle size and measuring distance changing within 100 m on the measurement results are compared and analyzed. At the same time, the fugitive emission source is selected for actual measurement. The results show that the experimental measurement device based on the new method can be applied to the remote estimation of the mass concentration of particulates in the fugitive emission air mass in the open field.