Objective: To analyze the influence of malnutrition in the elderly patients with acute coronary syndrome on related factors and short-term prognosis. Methods: 415 elderly patients with acute coronary syndrome were selected.Comprehensive geriatric assessment was used to investigate the risk of acute coronary syndrome by examining coexisting diseases and using the NRS2000 score.The mortality and emergency visits were followed up. Results: The patients were divided into two groups according to NRS2000 score: malnutrition group (n=179) and non-malnutrition group (n=236). (1) In malnutrition group, the proportions of female, over 85 years old, more than 3 kinds of coexisting diseases were 47.5%(85/179), 11.7%(21/179), 62.6%(112/179), respectively, which were higher than those of the non-malnutrition group[36.9%(87/236), 4.7%(11/236), 41.9%(99/236)](χ²=4.732, 7.152, 17.318, all P<0.05). (2) In malnutrition group, the incidence rates of geriatric syndromes such as uracratia, falls, visual disorder, hearing disorder, constipation, sleep disorders, oral problems were 47.5%(85/179), 30.2%(54/179), 40.2%(72/179), 41.9%(75/179), 54.7%(98/179), 52.0%(93/179), 76.5%(137/179), respectively, which were higher than those of the non-malnutrition group[31.4%(74/236), 14%(33/236), 29.2% (69/236), 29.7% (70/236), 30.5%(72/236), 36.0%(85/236), 53.0%(125/236)](χ²=11.206, 16.092, 5.477, 6.707, 24.732, 10.577, 24.297, all P<0.05). (3) In malnutrition group, the incidence rates of coexisting chronic diseases such as hypertension, chronic obstructive pulmonary disease, heart failure, severe renal insufficiency, cerebrovascular disease, dementia, anemia, osteoporosis were 77.1%(138/179), 16.2% (29/179), 22.9%(41/179), 17.9%(32/179), 46.9%(84/179), 6.7%(12/179), 27.4%(49/179), 26.8%(48/179), respectively, which were higher than those of the non-malnutrition group[61.9%(146/236), 7.6%(18/236), 14.4%(34/236), 7.2%(17/236), 32.2%(76/236), 1.3%(3/236), 13.1%(31/236), 17.4%(41/236)](χ²=10.931, 7.451, 4.965, 11.137, 9.315, 8.624, 13.262, 5.388, all P<0.05). (4)Cox regression analysis showed that malnutrition risk score was the independent risk predictor for all-cause mortality (HR=0.034, 95% CI: 0.072-0.904) and emergency department visits (HR=0.328, 95% CI: 0.197-0.548) in elderly patients with acute coronary syndrome. Conclusion Comprehensive geriatric assessment and nutritional assessment are useful to evaluate the clinical features of acute coronary syndrome in elderly patients.Malnutrition risk score is an independent predictor of all-cause mortality and emergency treatment in elderly patients with acute coronary syndrome.