Objective:To assess the infuence of preload on Tei index(including PW-Tei and TDI-Tei) to evaluate left ventricular function. Method:Twenty-seven patiens with PDA and 32 patients with VSD without other diseases were studied. PW-Tei,TDI-Tei,LVEF,Vp,LVEDD and LVESD were calculated before and after the surgical operation. Results:Either PW-Tei or TDI-Tei increased while the LVEF,LVEDD and Vp decreased signicantly after operation. Conclusion:Both the PW-Tei and the TDI-Tei were influenced by preload when they were used to evaluate the left ventricular function.