Abstract: The paper introduced principle, characteristics and applicable situation of water level detection of float type, capacitive type, pressure type, ultrasonic wave type and bubble type. It indicated that the technologies of water level detection have different characteristics: float type water transmitter is suitable to detect water level of water tower and reservoir with the maximum water of depth 6 m and clear water quality; capacitive type water transmitter is suitable to detect water level of rivers and lakes with clear water quality, big diameter of water container and deep water level; pressure type water transmitter is suitable to detect water level of well with smaller diameters of water container; ultrasonic wave type and bubble type water transmitter need be chosen carefully with complex structure and high cost although they overcome influence of water quality on measuring accuracy.