In this study, the dynamic response of human umbilical vein endothelial cells (HUVECs) to ITO quartz crystal electrodes was monitored by quartz crystal microbalance (QCM) and live cell imaging. HUVECs with different cell concentrations were added to the ITO electrode. Realtime changes of QCM resonance frequency and dissipation were measured and compared with different concentrations of HUVEC. Through the combination of ITO electrode and optical microscope, the dynamic changes of HUVEC before and after drug treatment were also monitored. The Cell Viscoelastic Index (QCM ratio of dynamic resistance change to frequency shift, CVI=ΔR/ΔF) was used to characterize the cells’ viscoelasticity, at the same time the changes  of cell morphological were realtime monitored by living cell imaging technology. The results showed that when the cell concentration was 10 000 cells/mL, the CVI was the maximum on the ITO electrode and HUVEC spread completely. The morphological changes of the cells were not obvious under the realtime monitoring of the microscope before and after drug treatment, but the  changes of CVI was great . The results showed that the QCM signal was more sensitive than the optical signal.