The invention discloses a flow control method, device and system. The method comprises the steps of analyzing input messages in a current time domain, and obtaining a length value of each input message; reading cache message information about a memory in an internal register; obtaining an input total flow value according to each input message length value and the cache message information; if theinput total flow value is smaller than a preset flow threshold register value, judging whether a message is stored in a memory or not, if the message is stored in the memory, taking out the stored message, outputting the stored message and subsequent input flow to a server together, and meanwhile, updating a message reading initial address and a pre-read first message length value in cache messageinformation; and if the flow value is greater than or equal to the flow valve register value, storing the subsequent input flow into a memory, and meanwhile, updating a message storage ending addressin the cached message information. The method, device and system have the beneficial effects that servers and complex operations do not need to be added, and the integrity of the messages is kept bysacrificing the timeliness of part of the messages.