The invention discloses a real-time monitoring calculation system and method for shipborne static draught. A data acquisition module is adopted to obtain initial draught data and initial data associated with draught calculation when a ship is out of harbor, real-time data associated with the draught calculation is monitored in real time during the navigation of the ship, and a data processing module is adopted to obtain the real-time static draught of the ship through the calculation based on a computational model of ship draught according to the initial data and the real-time data; meanwhile,the calibration is performed through combination of the draught data obtained according to the bottom pressure of the ship when the ship waits in the harbor. By adopting the real-time monitoring calculation system and method, more accurate draught data can be calculated without the need for the ship to stop the navigation, and the influence on the draught calculation of the ship owing to navigation environment factors is also overcome.