The macroscopical survey and mapping of soil erosion are generally carried out by many units that use many maps, thus there are some errors of attribute and position of polygons between these units and maps.The seamless joint of map comes true through GIS (Geographic Information System), but GIS can not resolve attribute errors.The procedure, principal and the methods of vector map joint are put forward.For the high work efficiency, three methods based on GIS can be selected according to the size of maps and corresponding images, which are jointed in a single coverage reunited by two coverages, switch in the current and backg round coverages and joint the part/parts split form original map/maps.