Abstract: Objectives The present study aimed to investigate the effect of homocysteine （Hcy） and lipoprotein （Lp） （a） on the degree of coronary artery injury and the extent of injury. Methods A total of 548 consecutive patients who receive coronary angiography and percutaneous coronary intervention in Ma'anshan People's Hospital from January 2015 to November 2017 were enrolled. According to the results of coronary angiography, Hcy and Lp （a）, we analyzed the correlation between Hcy and Lp （a） levels and coronary artery injury, evaluated the effect of elevated Hcy and Lp （a） on the extent of coronary artery injury and the degree of injury. Results ①Multiple factor regression analysis showed that both Hcy and Lp （a） were independent risk factors for coronary heart disease（P<0.05）. ②The patients in group Hcy and Lp（a） increased simultaneously had more lesions of three coronary arteries than other groups （P<0.05）. The concentration of plasma Hcy and Lp （a） in the three branches disease was higher than that of single branch disease （P<0.01）. ③The patients in group Hcy and Lp （a） increased simultaneously had significantly higher Modified Gensini Score compared with the other groups （P<0.05）. Conclusion The level of plasma Hcy and Lp （a） is positively correlated with coronary artery injury. Both of them have synergistic effect for coronary artery injury.