Abstract: Wettability is an important parameter in water flood- ing development,because it determines oil-water micro -distribution and capillary and its direction in rock pore and throat.Wettability in Daqing periphery oilfield is studied in this paper and the wettability mainly appears as hydrophilicity.The analysis of the influencing factors of wettability in Daqing periphery oilfield shows that hydro- philicity decreases as non-hydrocarbon and asphaltene increases;while hydrophilicity increases as water salinity and irreducible water saturation increases.In order to have a better understanding of wettability,a mathematical model between wettability index and angle of contact is established.This model can be used to determine the av- erage angle of contact,reahze accurate transformation be- tween capillary curve based on mercury and oil-water capillary curve under the condition of reservoir,and pro- vide reliable support for pore structure,relative permea- bility prediction and reservoir numerical simulation.