Abstract: The well resistance and smear effect are generally existing in soils treated with prefabricated drains , but they are always ignored in design. In this paper, the well resistance and smear effect are analyzed and some transformation curves are given, it is suggested that G =0.15 and J =0.3 can be the criteria whether to consider the well resistance and smear effect or not, giving a simple and rational method in analyses and design for the non ideal well.