The invention relates to the technical field of water conservancy projects, and discloses a water conservancy project overwater operation warning and early warning device which comprises a base, a stand column, a lengthening rod, a waterproof box, a photovoltaic panel, a rainfall sensor, a radar water level gauge, a wind speed sensor, a camera and an audible and visual alarm. The stand column is installed on the base, the lengthening rod is detachably installed on the side face of the stand column, the bottom end of the lengthening rod is connected with the stand column through the stand column, and the photovoltaic panel is installed on the lengthening rod through the support. The overwater operation warning and early warning device for the water conservancy project and the using method thereof have the advantages that the water speed, the water level, the rainfall capacity and the wind speed are detected, the river channel environment is simulated, the environment change is analyzed, whether the overwater operation is dangerous or not at the moment is judged, early warning is conducted in time, and the danger caused by the environment can be effectively checked.