Abstract: The study focuses on the blockage of Escherichia coli during the recharge process of underground water source heat pumps.The migration and deposition of Escherichia coli in the pores and channels of Porous medium were dynamically observed through the selfdeveloped sand particle migration and deposition test system. In this paper, three test boxes with different lengths were used to carry out the migration and deposition of Escherichia coli in Porous medium. Through the test, the following conclusions were drawn: The internal friction force inside the quartz stone particles is conducive to the deposition of Escherichia coli, and the flow speed plays a key role in the microbial blockage caused by Escherichia coli; Three types of test boxes with different lengths（60, 80, 100 cm） were used as objects under the action of flow velocity, and the sedimentation rate increased by 57.1% for 100 cm and 80 cm; Compared with 80 and 60 cm, the sedimentation rate increased by 27.3%; The recovery rate of Escherichia coli is also positively correlated with fluid velocity, and its principle is similar to sedimentation rate. The experimental research conclusion has on-site guidance significance for microbial blockage in groundwater source heat pump recharge.