Nitrogen dioxide (NO₂) is one of the main pollutants in the atmosphere, which plays a key role in tropospheric and stratospheric atmospheric chemistry processes. It not only participates in the catalytic formation of tropospheric ozone, but also contributes to the formation of aerosols, which leads to climate disasters such as acid rain and endangers human health. NO₂ from anthropogenic sources (industrial, power plant, transportation, etc.) accounts for the majority of the total NO₂ emissions. Traditional monitoring methods, such as satellite remote sensing technology, are not sensitive enough to the bottom of the troposphere, while in-situ sampling instrument can only obtain the concentration information of pollutants near the surface. The multi-axis differential optical absorption spectroscopy (MAX-DOAS) technique, which has been widely used in recent years, is not only sensitive to near surface observation, but also has the advantages of high temporal resolution, low detection limit and simultaneous monitoring of multiple pollutants. In order to monitor the variation characteristics of the tropospheric column density of NO₂ in Shanghai in real time, a ground-based MAX-DOAS instrument was set up in Xuhui District of Shanghai for long-term continuous observation. By analyzing the MAX-DOAS measurement data from June to September 2019, it is found that NO2 VCDs generally reach the peak value (1.56×10¹⁶ molec·cm^-2) at about 9:00 in the morning, and the concentration decreases significantly with the increase of illumination, and reaches the lowest value (1.21×10¹⁶ molec·cm^-2) in the afternoon, and increases again after 16:00 in the evening. In addition, the NO₂ VCDs during the morning peak of weekday was significantly higher (about 11.8%) than that at the weekend, while the NO₂ VCDs in the weekend evening increased significantly compared with that in the weekday evening. Comparing the MAX-DOAS observation results with the data of TORPOMI satellite, it is found that two data sets have a good agreement, and the correlation coefficient R is 0.87. Using the HYSPLIT backward trajectory model to cluster analysis the backward trajectory of air mass transport at 500 m height during the campaign, it is found that NO₂ pollution in Shanghai is significantly influenced by the transportation of polluted air masses in coastal areas. Research shows that the ground-based MAX-DOAS system, as a real-time, rapid and continuous atmospheric monitoring method, can be widely used in urban area pollution monitoring applications. The observational research of tropospheric NO₂ in Shanghai provides some data support for the prevention and control of air pollution in Shanghai.