Objective. The objective of this study is to analyze the relationship between the electrolyte level of patients with acute ST-segment elevation myocardial infarction (STEMI) and short-term prognosis after percutaneous coronary intervention (PCI). Methods. The clinical data of 142 patients with acute STEMI who underwent PCI in our hospital from September 2018 to September 2019 were retrospectively analyzed. According to the level of serum sodium, potassium, and chloride in patients admitted to the hospital, they were divided into the normal electrolyte group (n = 78), the mild decline group (n = 46), and the severe decline group (n = 16). Univariate and logistic regression multivariate analysis of the relationship between patient electrolyte levels and general clinical data is performed. Statistical analysis of patients' adverse events within 90 days was performed. The Kaplan-Meier survival curve analyzed the relationship between the survival period and electrolyte levels in patients with acute STEMI without major acute cardiovascular events (MACE) within 90 days. Results. The levels of creatine kinase-MB (CK-MB), cardiac troponin I (cTnI), myocardial infarction area, and Gensini score in patients with mild decline were significantly higher than those in the normal group, left ventricle ejection fractions (LVEF) value was significantly lower than the normal group, and patients with severe decline were significantly higher in creatine kinase (CK) level than the normal group (P<0.05). The levels of CK-MB, CK, cTnI, and myocardial infarction area of the patients in the severe decline group were significantly higher than those in the mild decline group, and the LVEF values were significantly lower than those in the mild decline group (P<0.05). The levels of CK-MB, CK, cTnI, the area of myocardial infarction, and Gensini score in patients with acute STEMI have an independent effect on their electrolyte levels. The patients in the mild decline group and severe decline group had significantly higher rates of cardiogenic shock, heart failure, ventricular aneurysm formation, ventricular septal perforation, or death within 90 days after PCI. The median without MACE survival time of patients with mildly and severely reduced electrolyte levels was significantly lower than that of patients with normal electrolyte levels. Conclusion. Patients with acute STEMI are prone to electrolyte disturbances, and their CK-MB, CK, and cTnI levels; myocardial infarction area; and Gensini score have independent effects on electrolyte levels. Patients with electrolyte disturbances are prone to poor prognosis after PCI, and their survival period without MACE at 90 days is significantly lower than that of normal patients.