The method of filling grid dummy values of potential field based on heat conduction model is proposed in this paper, the process of filling grid dummy in blank areas is regarded as a process of heat conduction to achieve grid data transferring from the known effective information to missing data areas, thus gradually completing data interpolation in blank areas. The numerical experiments show the method of filling grid dummy values by heat conduction model has high precision and is obviously effective. The contours are continuous and smooth on the edges, and also can truly reflect the features and trend of abnormal gradients. The application to the real airborne gravity data indicates that the method is feasible and practical, the effect of filling grid dummy can well conform with the variation law and reflect more geological information of regional gravity field, thus improving the accuracy of data processing and transformation in potential field. The method has practical significance.