Through hydrogeological investigation, geological drilling, pumping tests, hydrochemical analysis and other methods, a comprehensive study has been conducted on the enrichment law and hydrochemical characteristics of groundwater in Cretaceous volcanic rocks in Fangcheng basin in Linyi city. It is found that volcanic rocks in Fangcheng basin and the surrounding volcanic debris rocks constitute a vein type volcanic rock water storage structure with water supply significance. The water storage structure of Qianhuoshan rock has moderate water richness, with a unit water inflow of 18.7~310.7m3/(d · m) for drilling. The total dissolved solids in groundwater are generally less than 1g/L. The hydrochemical types are mainly HCO3 Ca type, HCO3 Ca · Mg type, HCO3 · Cl Ca type, and HCO3 · Cl Ca · Mg type. The water quality is good, and it can be used as one of the target aquifers for drought resistant well drilling in areas with poor water in volcanic rocks. This discovery is of great significance for solving the problem of centralized water supply sources for rural areas in Yimeng Mountain volcanic rock poor water area.