Because of the importance of formaldehyde in atmospheric photochemical reaction and its harm to environment, climate and human health, it is urgent to control and monitor the concentration of formaldehyde. At present, traditional monitoring is mostly limited to indoor monitoring based on chemical methods and chromatographic methods or outdoor monitoring in a small range, while outdoor formaldehyde monitoring in a wide range of atmosphere is often ignored by people. In order to effectively monitor the concentration of formaldehyde (HCHO) in the atmosphere, the ground-based MAX - DOAS observation system was established. Compared with the active DOAS, the MAX - DOAS observation system was not limited by the light source and reflex attachment, with simple platform construction, wide measurement range. Based on this, continuous observation experiments were carried out based on MAX - DOAS observation system in the summer of 2018 at Hefei site, combined with the new generation of spectral processing software QDOAS, the nonlinear least squares fitting of DOAS algorithm was used to retrieve the differential slant column densities of formaldehyde (HCHO). Then the differential slant column densities of formaldehyde were converted to the vertical column densities by use of the atmospheric quality factor (AMF), and the observed data in July were analyzed, the result showed that the slant column densities of formaldehyde under low elevation angle are higher, therefore, tropospheric formaldehyde is mainly concentrated in the position near the earth’s surface. It can also be seen from the experimental data that the change trend of nitrogen dioxide and formaldehyde is basically consistent, indicating that the atmospheric formaldehyde is correlated with the nitrogen oxides (NO2, etc.) discharged by motor vehicles or industry in the process of atmospheric source and sink. It was found that the change trend of the two kinds of measurement data had a good consistency by the comparison between the ground-based MAX - DOAS measurement data and the OMI observation data, and the correlation coefficient was 0.518 9, and the reason why the OMI observation value was low was analyzed. The results showed that the ground-based MAX - DOAS system can not only study the evolution of regional pollution, but also provide a real-time and rapid monitoring method for formaldehyde measurement, a new analytical method for analyzing the source of atmospheric formaldehyde, and an effective method for verifying satellite observation data.