The  influences of the level and the temperature of cold water in the channel released from reservoir on the temperature field of groundwater-surface water ecotone  is analyzed with mathematical models of coupled water and heat transfer in saturated porous media. The research shows that compared with thermal conduction and thermal blooming, the thermal convection plays a leading role in the transfer of underground water and heat during cold water infiltration. Water level in the channel determines the extent of the temperature field being affected, and water temperature mainly affects the  temperature variation  at each point in the temperature field.