An operation control system for a small boat can include a mode selection module configured to allow a driver to select between a plurality of driving modes including at least a normal operation mode, in which the boat cruises at a speed in response to the displacement of an acceleration controller, and a low-speed setting mode, in which the boat cruises at a preset low speed when a low-speed setting controller is operated; in which the mode selection module permits the driving mode to switch to the low-speed setting mode if the displacement of the acceleration controller is zero, or small or close to zero or is in or substantially at an idle position.