The invention discloses a control method, device and system capable of preventing accidental working state switch of a concrete pump truck. The control method includes: detecting whether a power output switch transmits a switch signal or not when the concrete pump truck is in a driving state; if so, extracting a transfer case rotation speed signal and gearbox state information from a chassis controller; transmitting a reverse control signal to a power take-off electromagnetic valve to facilitate that working state of the concrete pump truck can be changed into operation when transfer case rotation speed is zero and the gearbox is in a neutral position; simultaneously transmitting a switch control signal to the chassis controller to facilitate the chassis controller to adjust output power of an engine. By detecting the transfer case rotation speed and gearbox state, current working state of the concrete pump truck can be obtained accurately, working state switch caused by misoperation can be avoided effectively, and safe and reliable operation of the concrete pump truck can be guaranteed.