Fire fighting truck foam proportion mixing control method, device and system and fire fighting truck

The invention relates to the field of vehicles, and provides a fire fighting truck foam proportion mixing control method, device and system and a fire fighting truck, the method comprises the following steps: obtaining a target foam proportion and a current liquid supply flow of a foam mixing system of the fire fighting truck, and determining a target foam flow based on the target foam proportion and the current liquid supply flow; generating an initial value of a foam flow control signal based on the target foam flow, and sending the initial value to a driving device of a foam pump in the foam mixing system; the driving device of the foam pump is used for driving the foam pump based on the foam flow control signal; the current foam flow of the foam mixing system is obtained, and when the current foam flow does not meet the target foam flow, the foam flow control signal is iteratively updated based on the current foam flow, the target foam flow and the initial value of the foam flow control signal. According