Abstract: The analytical technique of swipe sample particle analysis plays an important role in sample analysis of nuclear safeguard environmental sampling, and the first step of particle analysis is to search highly enriched uranium (HEU)bearing or Pu-bearing particles among dust particles. A new method for identifying HEU and Pu particles was established by using α track detection. First, an organic film containing particles was prepared and covered with a CR-39 solid state nuclear detector. After exposure, the detector was etched in a NaOH solution for different time, and the α track star parameters created by HEU or Pu particles were measured by optical microscope. The results show that the scatter plot of the dimeter of track end versus track minor axis can be used for HEU and Pu particles distinguishing when etching time is lager than 10 h, especially useful when track stars are concentrated.