CS2 has a great effect on human health and atmospheric circulation. The new research recently indicates that CS2 in the urban air may primarily come from combustion of coal. A new method for remote sensing of emission from point source was proposed, based on passive differential optical absorption spectroscopy (DOAS), by taking the sun's radiation as light source. The principle and system of passive DOAS were introduced, and the method of spectrum analysis for CS2, including choosing “zero” reference spectrum and reducing the Ring effect for the spectra evaluation was discussed. CS2 in power plants’ emission plume is measured and the column density of CS2 is successfully retrieved. It indicates that burning of coal produces certain CS2 and provides useful evidence for research of main source of CS2.