In order to study the effect of low-salinity water composition on the surface charge, wettability and oil film desorption capacity of rock and crude oil as well as the relationship between them. low-salinity water prepared by different ions in varied ionic concentrations and pH values were mixed with simulated rocks and crude oil samples to measure the Zeta potential value，respectively. The solid/brine water/crude oil three-phase contact angle was measured on the man-made core slices. The oil film desorption capacity on the surface of rock particles mixed with brine water was measured. The experiments showed that the effect of Na , Ca2 and Mg2 ions on the surface charge of crude oil and rock are mainly depended on the ionic valence state. The divalent ions have a more significant influence on the negative charge. The negative charge detected in solutions of the same ions decreases with the increase of the concentration of ions. The effect of increasing pH on negative charge is related to the ionic valence and the dehydration of solutions. The negative charge of the divalent Ca2 or Mg2 ion is less than that of the monovalent ion solution, and displayed a trend that the negative charge increased initially and then decreased，which differs from the latter . The results indicated that the effect of low-salinity water on the surface charge of crude oil and rock is consistent with the influence on the interfacial contact angle and the oil film desorption capacity. As the absolute value of the Zeta potential decreases, the interfacial contact angle increases and the oil film desorption decreases.