Objective To find up a suitable beginning scan time so that to assure the image quantity during CTA of brain.Methods 30volunteers were checked by heart colour sonography first,then CTA at earlier stage was done,when the density in basilar artery high up to120 HU,that time was regarded the time as beginning scan time,the relative curve between beginning scan time and ejection fraction(EF) was drew,according to this relative curve,34 patients were examined by CTA,the displaying situation of vessel was evaluated comparatively with DSA in part of patients.Results According to this method,the successful rate of CTA in patient’s group was 100%,the trunk of brain vessel and its 1~3 level branch were showed in 100%,the 4~5 level branch of middle cerebal artery showed in 94.1%(32/34).Conclusion According to EF of heart to determine the beginning scan time of CTA is practical,that the image quantity of CTA can be assured.