The RAPD marker OPP01/700 proved to be linked to the Fusarium wilt resistant gene in watermelon wild germplasm PI296341 was cloned and sequenced, and transferred into a SCAR marker. The linked marker was tested to be one copy by Southern blotting. The technique of detection of the SCAR-amplified products was simplified. These techniques were applied in selecting resistant plants in F3 of the introgression of the disease resistant gene. It is the first report in this field of transfer ring a RAPD marker linked to disease resistance gene into SCAR marker, and establishing the technique of molecular marker-assisted-selection for breeding Fusarium wilt resistance cultivars.