For Patients with coronary artery disease (CAD) accompanied by decreased left ventricular ejection fraction (LVEF), coronary artery bypass grafting (CABG) was the preferred management and superior to pharmacological therapy alone. Health assessment related to the quality of life in patients with CAD and post-CABG is important and intended for evaluating the acquisition of the therapeutic target. Based on the guidelines, treatments of CAD should be accompanied by lifestyle modification and cardiac rehabilitation. The aim of the study was to assess functional capacity changes (∆METs) after phase II cardiac rehabilitation as a predictor of quality of life 3 months after CABG. A cohort study methods on patients with LV systolic dysfunction who underwent CABG between January 2019 and January 2021. Patients were submitted to phase II cardiac rehabilitation, where ∆METs showed changes in functional capacity before and after the program. The abnormality of ∆METs as a predictor was determined by the cut-off point using ROC and AUC curve in the previous study which was 3.25 METs.5 Observe-component was patients’ quality of life 3 months after CABG using Kansas City Cardiomyopathy Questionnaire (KCCQ). The study showed there was a significant relation between ∆METs and KCCQ scores with moderate strength (p<0.01; r = 0.592), and showed the lower ∆METs group had a 5.3 times greater risk of poor quality of life than the higher ∆METs group 3 months after CABG (p<0.01; OR = 5.3). The conclusion of the study showed that Functional capacity changes after phase II cardiac rehabilitation could predict the quality of life after CABG in patients with LV systolic dysfunction by using KCCQ.