The effect of wettability on recovery and relative permeability by waterflood test and the method of controlling rock wettability by aging crude oil are studied in this paper.The results show that waterflood recovery of weak water-wet rock is the highest;the oil relative permeability of water-wet rock is higher than that of oil-wet rock;the adsorption of heavy polar materials in crude oil can effect the wettability of rock surface and oil-wet may be ehanced with the increase of aging time.