To realize a sustainable development strategy, it is important to explore the influencing factors of air pollutants. Daily monitoring data for nitrogen dioxide (NO₂) in Shandong Province from 2014 to 2019 were used in the geographical detectors to analyze the influencing factors. Through geographical detection, the action of influencing factors and their interactions on spatial heterogeneity were explored. The main influencing factors of NO₂ concentration were the daily temperature range and industrial smoke dust emissions, with q values of 0.4625 and 0.388, respectively, and the interaction effects of most influencing factors were characterized by bilinear enhancement. The interaction between urbanization rate and increases in secondary industry was the strongest, with an average 6-year q value of 0.716, followed by the interaction between the daily temperature range and increases in secondary industry, with a q value of 0.705. NO₂ air pollution was more severe in winter than in summer. The results indicate that we should take corresponding measures to control and reduce NO₂ air pollution based on the main influencing factors and their spatiotemporal characteristics.