Abstract: Separating up going and down going wave field efficiently is the most fundamental and crucial part in VSP data processing.The median filtering is a simple but effective method for wave field separation, but conventional median filtering method is only suitable for simple linear wave field separation.In this paper, a radial median filtering method is proposed and realized and the new method amend the old one when radial linear interference wave field exists in data, in this situation, the new method can separate wave fields in just one time.VSP data processing test shows that this new method is more efficient in separating up going and down going wave field of VSP data, and also good in separating P and P-SV wave field of VSP data, and will have a good application in surface wave suppression and surface wave extraction.