The invention discloses a made-in-China satellite laser altimeter on-orbit geometric calibration method and a made-in-China satellite laser altimeter on-orbit geometric calibration system. The made-in-China satellite laser altimeter on-orbit geometric calibration method comprises the steps of: measuring terrain of a calibration field by utilizing an airborne laser radar or GPS before satellite top-crossing; fitting a surface geometry model of the calibration field by adopting laser radar point clout data or ground GPS measurement data; and placing a laser point of a satellite laser altimeter on a known plane as a constraint condition, establishing a satellite laser altimeter strict geometric calibration model, utilizing a least square principle, and solving a geometric calibration parameter of the satellite laser altimeter. The made-in-China satellite laser altimeter on-orbit geometric calibration method and the made-in-China satellite laser altimeter on-orbit geometric calibration system can effectively solve the problem that positioning precision of a laser spot is not high due to installation deviation of the satellite laser altimeter and errors of laser range finding by utilizing ground natural terrain during satellite transition, increase measuring precision of the made-in-China satellite laser altimeter, and have high applicability and practical value.