The invention discloses a method, device and system for flow control. According to the core idea of the method, device and system for the flow control, a data set formed by flow of liquid or gas and control parameters is taken as a base, two parameters are obtained by means of least square operation, the corresponding linear relation between the flow of the liquid or the gas and the control parameters is obtained through the two parameters, and then a corresponding control parameter can be obtained according to the corresponding linear relation between the flow of the liquid or the gas and the control parameters under the condition that the flow of the liquid or the gas is available. Therefore, the proportion integration differentiation (PID) control method or other control methods are not needed for finding out size of the control parameters, and thus the over-control phenomenon caused by the PID control method is avoided. According to the method, device and system for the flow control, the flow of the liquid or the gas can be controlled accurately, stable, real-time and reliable flow control can be achieved, and technological requirements and enterprise expectations are met.