The small water surface evaporator uses the high precision weighing principle to measure the liquid weight in the evaporating dish, and then calculates the liquid level height. It can be used in a variety of environments, such as liquid or ice can be measured, disadvantage solved using the principle of ultrasonic measurement of the liquid level (easy to damage the sensor, 1. ice measurement to 2. when there is no water 3. low precision), can be used with automatic weather stations or professional evaporation recorder, used in agriculture, forestry, meteorological research and other relevant departments.