The invention discloses a satellite-borne occultation real-time forecasting method. The method comprises the steps of: obtaining the position velocity of a spacecraft according to the positioning device of an occultation detector; calculating the orbit parameter of the spacecraft; calculating the position velocity of the spacecraft and all navigation stars after 10s; calculating the pitch angle, the azimuth angle, the tangent point height of all navigation stars and the antenna azimuth angle of the spacecraft; judging whether the obtained pitch angle Elv, the tangent point height Hight and theantenna azimuth angle satisfy the threshold of the occultation event extrapolating the time for 30 s and 1 min, repeating the above calculation and determination processes if satisfied; and determining that the navigation star is the occultation if all are satisfied. The method of the invention adopts a continuous arc to judge the occultation event through an inertial navigation device, and enhances the accuracy of the forecasting result. The method is simple and easy to implement, and has important application value for real-time forecasting.