Abstract: In order to demonstrate the easy-running-down ability of hydraulic feedback heavy oil pump, on the basis of analyzing the operational principles and stress state of this pump, a polished load calculating model of the pump is established for heavy oil wells with hydraulic feedback heavy oil pump during production mixed with light oil. By comparing it with the calculating model of the commonly-used tube pump, the performance of easy running down for the hydraulic feedback heavy oil pump is found, and the factors which affect the down stroke are analyzed. Using the model to calculate the polished rod load for Well A which is producing heavy oil mixed with light oil, the errors are within 10% compared with the field measured data, which proved the reliability of the model.