The invention discloses an inter-ship distance real-time determination system and method under icebreaker navigation, and the method comprises the steps: 1), collecting sea ice environment data of a ship navigation region and the ship information of an icebreaker and a navigated ship, and calculating the ship suggested speed of a ship under a specific ice condition according to a polar region iceregion navigation system; 2) according to the historical data of the ship navigation speed, extracting ship navigation speed distribution under icebreaker navigation protection to obtain fitted speeddistribution; 3) establishing a ship following distance simulation model, and calculating the shortest safe following distance; and 4) comparing the real-time car-following distance measured by the distance measuring device with the shortest safety car-following distance output by simulation, and carrying out early warning according to the comparison result. According to the method, the collisionrisk between ships under icebreaker navigation protection is effectively reduced, the navigation safety of the arctic-ship-route ships is guaranteed, and the method has guiding significance for determining the following distance under the arctic-ship-route ship formation navigation operation mode.