Using GIS, the authors studied an area of 5713 km2 in Hohhot, Inner Mongolia. The reference values of Cd in four subtypes of surface soil were established. An analysis of 933 soil samples has revealed that the reference value of Cd in new accumulative topsoil of Hohhot is highest (0.107 mg/kg) ,and that in light cinnamon topsoil is lowest(0.084 mg/ kg).The results obtained provide basic materials for the construction of the local soil environmental quality standard.