Abstract: As viewed from the hydrogeochemistry of Cretaceous groundwater in the south of Baiyu mountain of the Ordos basin,the article is focus on the groundwater horizontal distribution and the water chemistry about surface water base-flow.By combined with the geology structure frame and lithofacies paleo-geography,the authors study the recharge,runoff and discharge of the region.By analysis them,the authors can draw conclusions:the region has horizontal distribution of Cretaceous groundwater hydrogeochemistry from east and north and southwest to center.And the more complex the water quality is and the higher the TDS istoward the center of basin; the change of water quality in the Malian riverindicate that groundwater of the east and west side recharges the river.The authors consider that the east and the southwest area in the southern parts of Ordos basin is groundw ter recharge range,the center is discharge,the Tianhuan syncline and the Malian river valley is discharge passage.