AnovelmethodtocorrectdiffractioneffectinmeasurementofultrasonicvelocityandattenuationathighfrequenciesisdevelopedbyusingthesuperpositiontechniqueofGaussianbeams.Toexaminethevalidityofthisnumericalapproach,theamplitudelossandphaseadvanceduetothediffractioneffectforanSiO2specimenarenumericallycalculatedin30-240MHz,andtheresultsareingoodagreementwiththosebythePapadakismethod.