Abstract: Cable pressure sampling technique has been used widely in Bohai Oilfield. In the conventional method, the interpretation of pressure data is commonly conducted by plotting the cross plot of formation pressure with depth, and calculating the fluid density by linear regression, and then determining the fluid interface. Based on the principles of the conventional method and the experience and inspiration obtained from the pressure measuring operation in many years, the authors summarized the rule of formation pressure coefficients changing with the depth and inferred the relationship between the pressure coefficient and the depth. The formula matches with the actual situations well and has been applied successively in practice. Therefore, it can be used as a new method for the interpretation of pressure-measuring data.