The present disclosure relates to an apparatus for detecting a distance between a carrier and a plate, the apparatus comprising: a base provided on the carrier; a rotation mechanism rotatably provided on the base and configured to rotate when the carrier is in contact with the plate during movement of the carrier relative to the plate; a rotation angle measuring mechanism configured to measure a rotation angle of the rotation mechanism so as to obtain the distance according to the rotation angle. The distance between the carrier and the plate can be calculated based on the rotation angle of the rotation mechanism, so that accurate measurement of the distance between the carrier and the plate can be realized. Further, the operation performance of the gap detection apparatus would not be affected or damaged by the vacuum environment.