The gravity valveless filter has the characteristics of large water production and simple operation,and is widely used.In order to improve the backwashing effect,the induced forced backwashing measure was adopted,and the induced forced backwashing device was designed,and the pump vacuum mode was used to form a pressure difference at regular interval,and the forced siphon was used to realize the regular backwashing,so as to ensure the quality and quantity of effluent.The working principle,type selection design of gravity valveless filter were introduced,and the application of measure to improve the backwashing effect was analyzed.