The higher level of positioning accuracy and realtime performance would be reached if receivers can achieve more prior information in the precise point positioning. In the undifferenced uncombined PPP, if the ionosphere delays supplied by augmentation stations can cover the precision demand, the estimated parameters must be less, the model must be more robust, the position precision must get better. In this paper, interpolation models has been discussed, a comparison in accuracy of interpolation of atmospheric correction has been done.,a new method named planar double spline curve interpolation has been delivered. The experimental results show that when the interpolation model is appropriate, the precision level of interpolation correction can meet the requirements of PPP.