Abstract: Reflectivity of ground truth is an important information of remote sensing.Experiments in lab are carried to study characteristics of microwave reflectivity in order to provide guidance for practice.In the first,how to transform the lab near field data to the natural far field must be solved.In this work,microwave reflectivity in the near field and retrieval of the near field data to the far field condition are studied theoretically.In the last,the correction is checked experimentally by microwave reflectometer.