Abstract: Objective To investigate the feasibility and accuracy of bedside ultrasound measuring peak velocity variation of common carotid artery to estimate preload of the patients in surgery ICU. Methods In this prospective cohort study, SICU patients with sinus rhythm and positive pressure ventilation were included. The peak velocity variation in common carotid artery(ΔVpeak)during each respiratory circle was measured by ICU resident with short-term training and experienced attending songrapher. Stroke volume before and after the fluid challenge was also measured by the experienced songrapher as the gold standard of fluid responsiveness. Then the ROC, feasibility and accuracy of the diagnosis trial were analyzed. Results There were 46 patients included. The peak velocity variation of common carotid artery measured by the attending(ΔVpeak1)is highly related with ΔSV(r1=0.76,P<0.05). Area under the receiver operating characteristic curve was 0.95 (P<0.05). The peak velocity variation of common carotid artery (ΔVpeak) >12.1% predicted fluid responsiveness with sensitivity of 90.9%,specificity of 83.3%, positive predictive value of 83.3% and negative predictive value of 90.9%. The peak velocity variation of common carotid artery measured by the resident(ΔVpeak2)were highly related with ΔVpeak1.(R²=0.68,P<0.05), the AUC was 0.94. Conclusion Measurement of peak velocity variation of common carotid artery with bedside ultrasound can accurately estimate the volume status of the patients in surgery ICU,and it is easy to be performed by the residents of ICU.