Abstract: Total dose 3KGy（Si） is supposed to the VDMOS specimens,and the degradation of VTH,gm,IDsub and Ron after experiment are compared with the initial value before experiment.The paper studied the variation of the parameter after the long term room temperature storing and after the annealing,then the explanation is given.Experiment results showed that,each parameter of the specimens was found degradation after the γ-ray irradiation.The average degradation of VTH of A Class Sample is 4.5V,and the average degradation of VTH of B Class Sample is 1.74V;The Growth of IDsub is over two orders of magnitude,the average growth of gm is 0.7S and the average degradation of Ron is 0.052Ω.When the specimens were storing at room temperature for a long time,each parameter got partial recovery.And after high temperature annealing the parameters can get recovery to the level before irradiation.