After research, it is found that only the female mosquito will beat human being when they are pregnant and try their best to dodge the male mosquuito simultaneity.Whats more, the mosquito has two kinds of natural enemy-dragonfly and bat.Base on this scientific discover, we design and create this electronic mosquito repeller.Imitating the flying sound of male mosquito and dragonfly,specially the buzz/ultrasonic which come from bat.