The disclosure relates to a method for determining the accuracy of a satellite-based navigation system for a vehicle during operation on a test route. The method includes providing a light beam propagating essentially perpendicularly to the direction of travel along the test route at each of two selected measurement points on the test route. Upon detection of the light beams impacting the vehicle perpendicularly to the direction of travel, a detection of the position and the direction of travel measured by a receiver of the satellite-based navigation system is triggered by means of an optical triggering device fastened on the vehicle. Finally, an accuracy of the satellite-based navigation system is determined on the basis of the two detected positions and directions of travel and position coordinates of the two selected measurement points. The disclosure also relates to a corresponding system for determining the accuracy of a satellite-based navigation system.