Based on the hydro-geological investigation of groundwater in Pingshan area of Yibin City, the groundwater occurrence environment, such as stratigraphic distribution, formation structure and water-bearing character in Pingshan area, is studied, the underground water is classified as pore water in loose rock strata, fissure water in bedrock, interlayer water in clastic rock and water in carbonate karst fissure. Through the analysis on the hydro-chemical characteristics of 122 groups of water sample in the study area, the spatial distribution map is established based on the Piper trilinear diagram; on this basis, the controlling factors of groundwater are explained by correlation analysis, principal component analysis and ion ratio coefficient analysis; and the spatial distribution characteristics of groundwater hydrochemistry in Pingshan area and the formation causes are revealed. The research results show that the groundwater in Pingshan area mainly are of HCO3--Ca2+, HCO3-·SO42--Ca2+, HCO3--Ca2+·Mg2+ and HCO3-·SO42--Ca2+·Mg2+ types, which is mainly influenced by the dissolution and filtration of stratigraphic lithology and atmospheric rainfall. The fundamental data is of great practical significance to guide the groundwater exploration and utilization in the Southern Sichuan.