Abstract: To analyze the chemical characterisitics and the formation mechanism of shallow groundwater in the Hangjing Banner gas field,this paper qualitatively evaluates the impacts of pollutants produced by gas field develop- ment on the groundwater environment,the GMS software simulates the migration law of pollutants in the groundwater environment,and also the corresponding preventive measures are proposed. Based on the new results,the authors sug- gest that:① Shallow groundwater in the study area locality has high mineralization which concentrated in groundwater depth is shallow. Moreover the major ion of shallow groundwater are Na+ and HCO- , the formation of groundwater chemistry is mainly composed of rock-weathering. ② The exploitation of gas will indirectly affect the groundwater chemistry,and gas field water infiltrate in the shallow groundwater which influences the cation exchange to change the groundwater environment. The drilling fluid and gas field water may cause the quality of shallow groundwater to be de- teriorated. After taking effectively protective measures,the gas field development has little impact on the environment of groundwater. ③ As a result of the simulation,the leaking of each pollutant has low concentration and low pollution scope in the predicted period. The standards of groundwater environment can be achieved after taking protective and anti-seepage measures. The seepage and production control of methanol wastewater treatment plant should be rein- forced,both of those can ensure to avoid the contamination of groundwater.