This paper systematically presents a knowledge-based geological prospecting system which is intended to provide consultation on geological mapping for the aerogeophysical prospecting interpreters. The system accepts the data of an aeromagnetic survey and an aeroradioactive survey, then it uses these data to identify magnetic anomalies and radioactive anomalies, to enclose the boundaries of the anomalous bodies, and finally to distinguish the lithologies of the anomalous bodies. Meanwhile, the system gives a confidence measure for each conclusion and answers the questions about the consultation. The capability of this system to provide the consultation relies on the knowledge the system has possessed. The knowledge has been offered by a panel of aerogeophysical prospecting domain experts.