Global warming, climate change and other issues caused by greenhouse gases have been the hotspot of international concern. CO2 is one of the important greenhouse gas, monitoring and controling of CO2 have been the focus of all countries. Based on the spectral absorption structure of CO2 in the 1.6 μm, the retrieval algorithm applied to obtain the CO2 column information from spectroscopic measurements was researched by using the weighted function modified difference absorption spectroscopy (WFM-DOAS) method. Based on atmospheric radiative transfer model, effects of the parameters on the sensitivity of the weighted function (WF) calculation were studied and simulated. The influence of different parameters on CO2 WF coefficient is calculated and analyzed in detail, including observation height, the solar zenith angle, solar azimuth, surface albedo, spectral resolution and so on. And based on the sunlight spectrum of zenith direction, the performance of the instrument, CO2 vertical column concentration and disturbance, and CH4 and H2O vertical column concentration were analyzed. And a preliminary analysis of the inversion error is better than 1%.