The atmospheric formaldehyde column concentration data of four provinces in Northwest China from 2005 to 2018 based on ozone monitoring instrument (OMI) were extracted, and their spatio-temporal change and influencing factors were discussed. The results showed that: in time variation, formaldehyde column had increased firstly and then decreased during 14 years, concentration of formaldehyde column in summer and autumn was significantly higher than that in winter and spring, and the average value in winter was slightly higher than spring. In terms of spatial distribution, formaldehyde column increased from west to east and north to south. High value areas were concentrated in Shaanxi, south-eastern of Gansu and south-western of Qinghai low value areas were concentrated in Ningxia, Qinghai and north-western of Gansu. Stability analysis showed that formaldehyde column was distributed in central and eastern parts, and the distribution was obvious. The main factors affected the change of formaldehyde column concentration including natural and human factors. In natural factors, concentration of formaldehyde column was signally affected by topography,wind direction and temperature. In human factors, it was positively correlated with population density, regional GDP, industrial waste gas emission and construction housing completion area. Among them, industrial waste gas emission was the main impact factor. There was a significant correlation between formaldehyde and aerosol particles in atmosphere. This further indicated that the change of formaldehyde concentration was affected by many factors, but aerosol particles, temperature and emission of industrial waste gas were the dominant factor.