Objective: To investigate the influence of coronary artery bypass grafting (CABG) under the guidance of coronary artery angiography fusion technique on myocardial microcirculation and cardiac function in patients. Methods: A total of 120 patients with multivessel coronary artery disease who underwent elective CABG in department of cardiac surgery of the 7th People’s Hospital of Zhengzhou from July 2023 to March 2025 were prospectively included and divided into fusion navigation group (n=60) and traditional angiography group (n=60) according to the random number table method. The fusion navigation group received coronary computed tomography angiography (CCTA) before surgery and CABG under the guidance of fusion system during surgery, while the traditional angiography group only completed surgery based on traditional coronary angiography (CAG) imaging. The perioperative indexes (surgical time, anastomotic orifice count, total flow of bridge vessels, length of stay in intensive care unit) were collected and compared between the two groups. Myocardial microcirculation indexes [index of microcirculatory resistance (IMR), coronary flow reserve (CFR)] and cardiac function indexes (left ventricular ejection fraction, left ventricular end-diastolic diameter, left ventricular end-systolic volume) were evaluated before surgery and at 6 months after surgery. The adverse cardiovascular and cerebrovascular events within 6 months after surgery were recorded. Results: The surgical time in fusion navigation group was shorter than that in traditional angiography group, and the total flow of bridge vessels was higher than that in traditional angiography group (P<0.05). At 6 months after surgery, the IMR, left ventricular end-diastolic diameter and left ventricular end-systolic volume in the two groups were reduced compared with those before surgery (P<0.05), and the indexes were lower in fusion navigation group than those in traditional angiography group (P<0.05). The CFR and left ventricular ejection fraction in the two groups at 6 months after surgery were enhanced compared to before surgery (P<0.05), and the indexes in fusion navigation group were higher than those in traditional angiography group (P<0.05). There was no statistical difference in the total incidence rate of adverse cardiovascular and cerebrovascular events between the two groups (3.33% vs 8.33%) (P>0.05). Conclusion: For patients with multivessel coronary artery disease, CABG under the guidance of coronary angiography fusion technique can effectively shorten the surgical time, enhance the blood flow of bridge vessels, improve the myocardial microcirculation function and promote the recovery of cardiac function.