The invention discloses a metabolic marker for diagnosing and distinguishing unstable angina pectoris and acute myocardial infarction, comprising one or more of N-phenylalanyl-L-glutamine, sphinganine, arachidonic acid, eicosatrienoic acid, glycocholic acid, lysophosphatidylcholine (14:0), tryptophan-arginine-leucine tripeptide, lysophosphatidylcholine (18:2), and lysophosphatidylcholine (20:3). In the single use of diagnosing and distinguishing patients with acute myocardial infarction and patients with unstable angina pectoris, each ROC (receiver operating characteristic) AUC (area under the curve) is greater than 0.7, and clinical diagnostic significance is provided; in the joint use for diagnosis, AUC further increases as a joint quantity increases, a highest AUC up to 0.991 is obtained in a case of nine members jointed, and sensitivity and specificity are respectively 99.2% and 98.9% under an optimal cutoff value. The metabolic marker can accurately diagnose and distinguish unstable angina pectoris and acute myocardial infarction, with high accuracy and high sensitivity and specificity.