One hundred and twenty-four Magnaporthe grisea isolates collected in four years from the Yanxi Blast Nursery, Hunan Province were tested for mating type with four hermaphroditic fertile isolates MAT1. 1 (KA3 and TH12) and MAT1. 2 (Guy11 and TH16) and the genetic diversity of 105 isolates were analyzed by using microsatellite markers(SSR). Among the 124 isolates, 28 belonged to MAT1. 1, 39 to MAT1. 2 and the remaining 57 to sterile ones, taking 22. 58%, 31. 45% and 45. 97% for each group, respectively. The 105 isolates could be divided into six lineages at 0. 67 similarity level based on the amplicons with seven pairs of SSR primers.