The utility model relates to a full-automatic water replenishing constant-temperature evaporating dish. The device comprises an evaporating dish, a water level sensor, a data acquisition controller, avoltage controller, a semiconductor chilling plate and a water replenishing assembly, a semiconductor chilling plate and an evaporating dish outer wall temperature sensor are mounted on the outer wall of the evaporating dish; the output end of the voltage controller is connected with the input end of the semiconductor chilling plate; the signal output end of the evaporating dish outer wall temperature sensor and the signal output end of the air temperature sensor are respectively connected with the signal input end of the voltage controller; the water supplementing assembly comprises a watersupplementing pool, a water supplementing pipe and a water supplementing electromagnetic valve, the signal input end of the data acquisition controller is connected with the signal output ends of thewater level sensor and the rainwater sensor, and the signal output end of the data acquisition controller is connected with the signal input ends of the water supplementing electromagnetic valve and the glass rainproof device. The automatic water replenishing device has the advantages that automatic data acquisition and automatic water replenishing can be realized, measurement errors caused by external environment influence are reduced, and errors of a measuring instrument caused by high temperature can be particularly reduced.