Objective To explore the diagnostic effects of double low dose CT angiography (CTA) and ultrasonic cardiogram (UCG) on acute coronary syndrome (ACS). MethodsThe clinical data of 124 patients with ACS were retrospectively analyzed. According to the"gold standard" coronary angiography (CAG) test results were divided into single-vessel disease group (n=23), double-vessel disease group (n=45) and multi-vessel disease group (n=56). The lesions degree (Gensini score), left ventricular ejection fraction (LVEF) and left ventricular end-diastolic diameter (LVEDd) double low dose CTA were compared among the three groups, and the accuracies of simple double low dose CTA, double low dose CTA combined UCG and conventional CTA grades were analyzed in the diagnosis of ACS. Results Gensini score and LVEDd level under double low dose CTA showed single-vessel disease group<double-vessel disease group<multi-vessel disease group, and LVEF level showed single-vessel disease group>double-vessel disease group>multi-vessel disease group (P<0.05). There was no statistically significant difference in the accuracy between double low dose CTA combined with UCG and conventional CTA grades in the diagnosis of ACS (P>0.05), but it was significantly higher than that of single double low dose CTA (P<0.05). Conclusion Double low dose CTA and UCG is ideal for the grading diagnosis of ACS, and its accuracy is similar to that of conventional CTA. And it is beneficial to optimize the patients' diagnosis and treatment experience by reducing radiation and contrast agent loading dose.