Abstract: This paper provided a new algorithm used in antenna's planar near field measurements to conduct near field and far field transformations.The far field patterns and performances of antenna under measurement can be obtained rapidly and efficiently by this method compared to some conventional methods,the precision is good enough.At the same time,the corrections of probe effect can be easily done and the effect of some key parameters in measurements can be easily discussed.This paper gives principles and calculation examples,and conclusions are reached.