Aim To study the effect of mean platelet volume (MPV) on the short-term prognosis of patients with acute coronary syndrome (ACS) after percutaneous coronary intervention (PCI). Methods 100 patients with ACS who underwent PCI in Xinyang Central Hospital from March 2015 to March 2018 were selected as the study subjects. According to whether adverse cardiovascular events occurred within one year after PCI, the patients were divided into two groups:the poor prognosis group and the control group. Then the differences of general clinical data, laboratory indexes, ultrasound indexes and PCI treatment between the two groups were analyzed. The influencing factors of prognosis were analyzed by COX model, and the predictive value of MPV on prognosis was analyzed by ROC curve. Results The rates of hypertension, diabetes mellitus, smoking and MPV, C-reactive protein (CRP) and low density lipoprotein cholesterol in the poor prognosis group were higher than those in the control group, and the proportions of thrombus aspiration and tirofiban use were lower than those in the control group (P＜0.05). COX regression analysis showed that smoking, elevated MPV and CRP were independent risk factors for poor prognosis (P＜0.05). By ROC curve analysis, MPV had a good predictive value for adverse cardiovascular events in ACS patients within one year after PCI, and the best cutoff point was 10.68 fL, the sensitivity of prediction was 70.73%, and the specificity was 72.22%. Kaplan-Meier curve analysis showed that the incidence of adverse cardiovascular events in ACS patients with increased MPV was higher than that in ACS patients with normal MPV (P＜0.05). Conclusions The increase of MPV is an independent risk factor for adverse cardiovascular events in ACS patients within one year after PCI. The MPV of more than 10.68 fL has a good predictive value for adverse cardiovascular events.