Different geochemical anomalies caused by different geological units are called Geochemical "Multi-Background" for short. There commonly exists more than one geological unit in numbers of 1:50 000 mapping. The geochemical anomaly values of some elements in different geological units can reach the difference as much as several to dozen times. In this case if we only use single anomaly value to draw the geochemical anomaly map, a large anomaly may appear in the high background area not related to ores; on the contrary, it is probable that nothing appears in the low background area which may contain a concealed ore boy. This paper discusses the difference of geochemical anomaly maps between single background and multi-background. According to the multi-background, there exist no boundary effects and displacement phenomena in the geochemical anomaly map, meanwhile the large anomaly in high background can be eliminated, and thus only the anomaly in low background that indicates the concealed orebody is displayed. The authors highly recommend using multi-background method to draw the geochemical anomaly map when there are many significantly different geological units in the work area.