The　autonomous　planning　and　scheduling　of　the　satellite　is　highly　dependent　on　the　accuracy　of　the　on-board　clock　which,　however,　needs　to　be　calibrated　by　the　external　information　such　as　Global　Navigation　Satellite　System　(GNSS)　or　Ground　time　service　system.　To　solve　this　problem,　this　paper　proposes　an　autonomous　on-board　clock　calibration　method　by　observing　the　Lunar　occultation.　The　steps　of　the　time　calibration　are　given.　The　crude　time,　firstly,　is　estimated　by　the　combination　of　star　trackers　and　sun　sensors.　Then　the　accurate　time　can　be　given　by　predicting　and　detecting　the　Lunar　occultation.　Meanwhile,　the　effects　of　the　attitude　sensor　precision　on　the　time　calibration　are　studied.　Finally,　the　validity　of　the　on-board　autonomous　time　calibration　algorithm　is　verified　by　simulation.　©　2022,　The　Editor(s)　(if　applicable)　and　The　Author(s),　under　exclusive　license　to　Springer　Nature　Singapore　Pte　Ltd.