Abstract: Traditionalintegraltimecalculationmodelscan′tsatisfytheaccuracyrequirement,becauseattitudeflexibilityandintegraltimechangeseverelyduringtheimagingofagilesatellite.Anintegraltimecalculationmodelwasproposedtoimprovetheaspectsofgroundvelocitycalculationofimagingpointandheightcalculationfromsatellitetogroundpoint.Digitalelevationmodelwasadoptedtocorrectheightvalueforheightcalculationfromsatellitetogroundpoint.Andtheattitudeangularvelocity′simpacttoangularvelocityvectorinthesatellitebodycoordinatesystemwasconsideredwhencalculatedthegroundvelocityatimagingpoints.ThewholealgorithmimplementationonOBDHsubsystemwasdesignedandsimulationcalculationundertheembeddedenvironmentwasconducted.Theanalysisresultsmanifeststhemethodcanmeettheaccuracyrequirementofagilesatellitecameraimagingqualitysincethedifferenceiswithin001‰bycomparisonwithSTKsimulationcalculationresults.

Key words: agilesatellite, integraltime, velocity-heightratio, digitalelevationmodel（DEM）, OBDHsubsystem