The invention discloses a control method and system for high-rise water supply and a fire fighting truck, and relates to the technical field of control. The method comprises the steps that work condition information input by a user is received, wherein the work condition information comprises a water supply mode and a water supply height; an engine revolution speed corresponding to the work condition information input by the user is automatically searched according to the corresponding relation between the work condition information and the engine revolution speed; a current engine revolution speed is controlled to reach the engine revolution speed corresponding to the work condition information input by the user, and therefore a current water supply height can reach the water supply height in the work condition information input by the user. According to the control method and system for the high-rise water supply, in the high-rise water supply process, the water supply height requirement can be met without the need for manually adjusting an accelerator, and user operation is facilitated.