Plasmafillingcandramaticallyimprovetheperformanceofhighpowermicrowavedevices.Thecharacteristicsofhigh-powermicrowavepropagationalongplasmafilledwaveguidesinanaxialmagneticfieldareanalyzedinthispaper,andtheponderomotiveforceeffectofhighpowermicrowaveistakenintoconsideration.Theoreticalanalysisandpreliminarynumericalcalculationsareperformed.Theanalysesshowthattheponderomotiveeffectwouldchangetheplasmadensity,distributionofmicrowavefieldintensity,anddispersionofwavepropagation.Thehigherthemicrowavepower,thestrongertheponderomotiveeffect.Indifferentmagneticfields,theponderomotiveeffectisdifferent.