Abstract: While conducting hydraulic fracturing,the flow rate is required to be controlled to enable the ball-off to block off and uncord the eyelet based on the stimulation process.To overcome the blindness in selecting flow rate in the traditional ball-off fracturing of separate layers,this paper studies the mechanism of ball sealers,sets up the flow rate control equation of ball-off fracturing of separate layers by taking the practical situation of the gas field in western Sichuan into account,determines the control flow rate at different perforation quantity,forms control techniques of minimal flow rate for ball-off fracturing of separate layers.Good results have been obtained in field application,which will be a good reference to the design and operation of ball separate-layer fracturing.