The invention provides an in-orbit calibration method for high precision imaging moment. The method comprises the following steps: step 1, acquiring the imaging moment sent from the ground on satellite; step 2, based on the acquired imaging moment, using the forecast satellite information from GPS receiver to acquire the satellite position and speed of the moment; step 3, based on the position and speed coordinated with the position of the imaging target point, calculating the calibrating the time deviation; step 4, calculating to obtain the calibrated imaging moment; step 5, judging whether the time deviation calibration meets the precision requirement. If not met, selecting the time acquired in step 4 to be the imaging moment, repeating the procedure from step 2 to step 5; if the requirement is met, the calibration calculation of imaging moment is completed, using the calibrated imaging moment to start the imaging device. The method has the advantages of low calculation burden and easy management for the satellite-borne computer. The method can be used for the determination of the high precision imaging moment during the normal working period of satellites, and provides a high precision time benchmark for the imaging.