In order to reveal the conduction mechanism of ZnO/p-Si heterojunction,the voltage-current characteristics of the heterojunction in ideal conditions are investigated based on the p-n junction diffusing model and the Anderson diffusing model,and the effects of doping concentration,working temperature and band compensation on the voltage-current characteristics are analyzed.The results indicate that（1） when the forward bias exceeds the built-in potential,the state of most carriers at the two sides of the interface changes from exhaustion into accumulation,thus forming reverse barrier to obstruct the movement of positive electric current in ZnO/p-Si heterojunction;（2） when the applied voltage equals the built-in potential,an inflection point occurs in the voltage-current curve;（3） when the applied voltage exceeds the inflection point voltage,the increasing speed of the current density with the voltage becomes slow;（4） the reverse saturation current density decreases with the increase in doping concentration of p-Si and with the decrease in working temperature,but it is insensitive both to the doping concentration of ZnO and to the conduction band offset;and（5） the applied voltage corresponding to the inflection point is positively related to the doping concentrations of p-Si and ZnO but negatively related to the working temperature and the conduction band offset.