Abstract: Gravity data processing is the foundation of gravity inversion and data interpretation. In gravity exploration, it is critical important to separate the local anomalies from the regional field. Compared to other algorithms, the interpolation cut method is an excellent one and the cutting radius is an important parameter to the method. In this paper, we computed the correlation through comparison of the local and regional anomalies as well as the comparison of the original gravity data and the terrain data. The best cutting radius is determined by the correlation. Our practice suggests that the interpolation cut method works well in separating the local fields from the regional in the South China Sea.