Abstract: Avariable-fidelitysequentialoptimizationmethodforreentrytrajectorydesignofaspaceplanewasproposedtoincreaserobustnessandaccuracyoftheoptimization.Theoptimizationprocessconsistedofthreesteps.Firstly,  therewasapreoptimization,inwhichforacoarsediscretecase,theoptimalsolutionofdesignvariablesforeachdiscretizedpointwasobtainedbyusingahybridoptimizationmethod.Secondly,  initialvaluesofthediscretizedpointsinarefineddiscretecasewereobtainedbyusinglinearinterpolationfromthepre-optimizationsolution.Finally,thetrajectoryoptimizationintherefineddiscretecasewasconducted,andmoreaccurateoptimizationresultswereobtained.Ademonstrationexamplewasusedtovalidatetheproposedmethod.Theresultsindicatethatthereentrytrajectoryoptimizationproblemcanbesolvedrobustlywithsatisfiedaccuracyandlesscomputationalburden.

Key words: spaceplane, reentrytrajectory, optimization, hybridoptimization, interpolation