Objective:To analyze the risk factors of patients with ankylosing spondylitis (AS) combined with premature coronary atherosclerotic heart disease (PCAD).Methods:A total of 74 patients with AS and coronary atherosclerotic heart disease (CAD) in Peking Union Medical College Hospital from January 1983 to July 2021 were enrolled. According to the age of onset of coronary heart disease, the 74 patients were divided into PCAD group and NPCAD (non-premature coronary heart disease) group. T test and Chi square test were used to analyze the data of the two groups, the risk factors for AS-PCAD were analyzed by multivariate Logistic regression. Results:① There were 37 cases in the PCAD group and 37 cases in the NPCAD group. In the PCAD group, there were 28 men and 9 women; wherease all were men in the NPCAD group. The difference was statistically significant ( χ2=10.25, P=0.001). ② Compared with the NPCAD group, the age of AS-PCAD group was younger [(23±10) years vs (29±12) years, t=-2.28, P=0.026], and the course from AS to CAD was shorter [(25±10) years vs (34±13) years, t=-3.00, P=0.004], hemoglobin (Hb) level was lower [(122±23) g/L vs(132±18) g/L, t=2.10, P=0.039], rate of anemia was higher [38.5%(14/37) vs 16.2%(6/37), χ2=4.39, P=0.037]. Proportion of increased C-reactive protein (CRP) was higher [65.5%(19/29) vs 35.5%(11/31), χ2=5.41, P=0.019]. ③ Juvenile onset AS (JoAS)[ OR(95% CI)=3.45(1.31, 9.10), P=0.012] and high levels of CRP [ OR (95% CI)=3.68 (1.44, 9.40), P=0.006] might berisk factors of AS-PCAD by multiple logisctic regression analysis. Conclusion:Patients with AS have a higher probability of PCAD, especially in those patients with JoAS, persistent inflammation and anemia. It is necessary to be alert to the risk of PCAD and early screening.