Objective To investigate the effect of graded nursing based on Modified Early Warning Score (MEWS) combined with comprehensive physical and mental nursing in severe heart failure due to coronary heart disease in the coronary care unit (CCU). Methods A total of 80 patients with severe heart failure due to coronary heart disease who were admitted to the CCU of our hospital from January 2020 to January 2022 were enrolled and divided into control group and observation group by drawing lots with balls, with 40 patients in each group. The patients in the control group received routine nursing andcomprehensive physical and mental nursing, while those in the observation group received graded nursing based on MEWS combined with comprehensive physical and mental nursing. The two groups were compared in terms of cardiac function parameters, quality of life, psychological state, prognosis, and the incidence rate of adverse events. Results Compared with the control group, the observation group had a significantly higher proportion of patients with grade I-II prognosis (95.00% vs 72.50%,P<0.05). After nursing, compared with the control group, the observation group had significantly better cardiac function parameters, quality of life, and psychological state (P<0.05). The observation group had a significantly lower incidence rate of adverse events than the control group (2.50% vs 22.50%,P<0.05). Conclusion For patients with severe heart failure due to coronary heart disease in the CCU, graded nursing based on MEWS combined with comprehensive physical and mental nursing can help to improve cardiac function, prognosis, and quality of life and thus holds promise for clinical application.