Background Few studies have investigated the association between air pollution and arterial stiffness in Chinese population, and the findings are inconsistent. The problem of multicollinearity exists when modeling multiple air pollutants simultaneously. Objective To investigate potential association between air quality index (AQI) and population brachial-ankle pulse wave velocity (baPWV) in Beijing. Methods This study retrieved medical examination data of 2971 participants from the Beijing Health Management Cohort, who were under 60 years old and not yet retired, from January 1, 2015 to December 31, 2019. The most recent medical examination data available were utilized for this analysis. AQI data from 35 air pollution monitoring sites in Beijing and meteorological data (including atmospheric pressure, air temperature, wind speed, and relative humidity) from 16 meteorological monitoring stations from January 1, 2014 to December 31, 2019 were collected. An average AQI exposure level for 365 d before the date of physical examination for each participant was computed using inverse distance weighting. Multiple linear regression analysis was employed to investigate the relationship between AQI and baPWV in Beijing, after adjusting for confounding variables including age, gender, body mass index, mean arterial pressure, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, fasting blood glucose, atmospheric pressure, temperature, wind speed, relative humidity, medication history of diabetes, medication history of hypertension, cardiovascular disease, education, smoking status, drinking status, and physical activity intensity. Subgroup analysis was performed by age, sex, presence of diabetes, and presence of hypertension. Results AQI demonstrated an overall decreasing trend during the study period and was lower in the northern regions and higher in the southern regions of Beijing. After adjusting the confounding variables, each 10 unit increase in AQI was associated with 6.18 (95%CI: 1.25, 11.10) cm·s⁻¹ increase in baPWV in all participants, 8.05 (95%CI: 2.32, 13.79) cm·s⁻¹ increase in the participants <50 years, 15.82 (95%CI: 8.33, 23.31) cm·s⁻¹ increase in the female group, 10.10 (95%CI: 4.66, 15.55) cm·s⁻¹ increase in the participants without diabetes, and 9.41 (95%CI: 4.21, 14.62) cm·s⁻¹ increase in the participants without hypertension. However, there was no statistically significant association observed between AQI and baPWV in the age group ≥50 years, the male group, the diabetic group, and the hypertensive group (P>0.05). Conclusion An increase in long-term AQI levels is associated with an elevation in the degree of arterial stiffness. Individuals under 50 years old, females, without hypertension or diabetes are susceptible populations to arterial stiffness when being exposed to air pollution. Improving air quality may contribute to prevent arterial stiffness.