A control method, system and apparatus for flow detection, a controller and a detection device. The method includes the controller acquires a flow identifier of a flow to be detected by each flow detection module in a network; adjusts the flow to be detected by each flow detection module according to a set load balancing policy; and delivers a detection instruction to each flow detection module, where the detection instruction includes a flow identifier of a flow to be detected by each flow detection module after the adjustment. In the present invention, because multiple flow detection modules are deployed in a network in a distributed manner, when there are a large number of switching devices included in the network, load balancing can be performed for detection of flows transmitted between these switching devices.