Abstract: In this study， Landsat 8 thermal infrared data was used to retrieve the water temperature around the outlet of Houshi Power Plant during the running period. Besides， an unmanned aerial vehicle（UAV）with thermal infrared sensors was employed to detect the details of thermal water distribution. The results show that the water temperature in the drainage areas of Houshi Power Plant decreases from the north to south， and the warm water flows southward along the coast after discharge. It spreads about 3 500 m southward and about 1 000 m sideward to the east and west. With the help of Pix4Dmapper software the thermal infrared images of UAV and the temperature profile of the areas covered by warm water are made. It shows that the water temperature at 300-500 m south of the outlet is lower in the west bank and higher in the east bank. The warm water does not spread evenly southward after discharged and it firstly spreads to the south along the east coast before it divertes to the west and then to the south．