Based on the eight hydrogeological supplementary exploration projects (four areas) constructed in the northern part of Ordos Basin from 2011 to 2017 in four areas, systematically collating and analyzing the data of groundwater Hydrochemistry in Cretaceous, the main influencing factors of groundwater hydrochemistry characteristics were summarized as follows: Climate conditions with obvious zoned regularity from southeast to northwest; Water-blocking edge formed by fracture structures in the West (water-blocking boundary) and North (water-blocking rock group) of Baoan Group. There was no unified and complete water-proof roof and floor in the vertical and horizontal directions in the Cretaceous interlayer water-bearing strata; The surface watershed of Anbian-Shililiang-Dongshengliang was roughly bounded by the vertical active alternating circulation between the eastern groundwater and the upper part; the vertical hydraulic connection of the Western groundwater was weakened; Cretaceous sandstone pore, the groundwater flow of fissure-fissure water was "deviated" from the middle (surface watershed) to the east, north and west; near the surface watershed, it was affected by cation alternating adsorption; on the east side of the surface watershed, it was affected by leaching and mixing; and on the northwest, it was evaporated-concentrated due to climatic factors.