Abstract: To study the effect of groundwater heat pump(GWHP) on groundwater environment, including hydrochemistry, water quality and microorganism, the paper analyzes the data from the interjection wells at regular intervals from July 2013 to October 2015 at a GWHP monitoring site in Shenyang. The result shows that GWHP has certain influence on the chemical types of groundwater (changing from the initial HCO₃·SO₄-Ca·Mg to early HCO₃·SO₄·Cl-Na·Ca, then to later HCO₃·SO₄-Na·Ca·Mg during the monitoring process) and growth velocity of microorganism controlled by temperature; the effect on the concentration of stable chemical compositions is little, while the concentration fluctuations of "three-nitrogen", Fe and Mn lead to the slight change of groundwater quality grade. Therefore, it is necessary to strengthen the effect monitoring of GWHP on groundwater environment.