A recombinant inbred lines（RILs）of 125 F₂S₇ progenies were derived from the cross，a watermelon line‘ Huayuanmuben’ with high sugar content as female parent， and a watermelon line‘ LSW-177’ with low sugar content as male parent. A genetic linkage map was constructed by using cleavage amplified polymorphic sequence（CAPS） markers. The map contained 245 CAPS markers and grouped into 11 linkage groups，spanning a total length of 2 423.9 cM，with an average gap of 9.9 cM between each marker. A quantitative trait locus（QTL） analysis was conducted by using composite interval mapping method（CIM） to locate fruit sugar content locus. A total of 4 QTLs related to soluble solids content were identified，showing 14.80%，11.50%，32.10% and 8.60% phenotypic variances，respectively. 3 QTLs related to fruit fructose content were identified，showing 8.80%，20.50% and 9.50% phenotypic variances，respectively. One QTL related to fruit sucrose and 1 QTL related to glucose content were identified，showing 11.34% and 24.10% phenotypic variances，respectively.These 9 QTLs showed a positive additive effect for sugar content means cultivar‘ Huayuanmuben’ contributed the favorable alleles.