Abstract: Genetic diversities of the total 30 monospore strians from 3 isolates of Fusarium oxyporum f. sp. niveum (Fon 1, Fon 2, Fon 3), which come from different areas of Hebei, were analyzed using 10 primers by RAMS (Random Amplified Microsatellies) molecular marker technique. Fon1, 9 polymorphic markers were obtained from the total 39 amplified markers; Fon2, 5 were obtained from the total 40; there are 4 polymorphic markers obtained from the total 40 markers in Fon3. The results showed that there existed genetic diversity among different monospore strains from the same isolate at DNA level.