To investigate the correlation between monomeric C-reactive protein (mCRP), pentameric C-reactive protein (pCRP) and IL-39 in peripheral blood and the degree of coronary artery lesions in patients with acute myocardial infarction (AMI).Methods From September 2020 to January 2021, 50 patients with AMI diagnosed by coronary angiography were selected as the experimental group, including 31 patients with ST-segment elevation myocardial infarction (STEMI) and 19 patients with non-ST-segment elevation myocardial infarction (NSTEMI), and 12 patients with scores ≤40 were classified as mild lesions by the Gensini scoring system. The Gensini scoring system was used to classify 12 cases with a score of less than 40 as mild lesions, 22 cases with a score of 40 points＜score≤80 were set as moderate lesions group and 16 cases with a score of ＞ 80 as severe lesions, and 20 patients who did not have any abnormalities or stenosis on coronary angiography at the same time as the control group. Venous blood was collected within 12h of admission, and mCRP, pCRP and IL-39 were measured by double antibody sandwich method, and HDL-C, TG, BNP, LDL-C, TC, LVEF, cTnI,CK-MB and Mb were measured. The two groups and the experimental group were compared, and the correlation between the degree of coronary artery lesions and mCRP, pCRP, IL-39 and other related indexes was analysed.Results There was no significant difference between the experimental group and the control group in terms of gender, BMI, mean age, history of hypertension, pCRP and history of diabetes mellitus (P＞0.05); TG, TC, LDL-C, BNP, mCRP, IL-39, cTnI, CK-MB and Mb were significantly higher in the experimental group than in the control group; HDL and LVEF were lower than in the control group, with significant differences(P＜0.05);there were no significant differences in gender, history of hypertension, history of diabetes, LDL-C, age, HDL-C, pCRP, cTnI, CK-MB, Mb (P＞0.05) and mCRP, LVEF, IL-39, BNP (P＜0.05) when comparing between the three groups of mild to severe coronary lesions within the experimental group.The Gensini score for the degree of coronary lesion was positively correlated with mCRP (r=0.656, P＜0.05), BNP (r=0.517, P＜0.05), IL-39 (r=0.609, P＜0.05) and negatively correlated with LVEF (r=-0.615, P＜0.05). Conclusion The degree of coronary artery lesions in AMI patients correlated with mCRP and IL-39 in peripheral blood. The higher the level of mCRP and IL-39, the more severe the lesions, while there was no significant correlation with pCRP, suggesting that the detection of mCRP and IL-39 has important reference value for the degree of coronary artery lesions in AMI patients