Abstract: The paper summarized the progress of sweet potato on the polyploid and karyotypes, development of molecular markers, construction of molecular genetic map袁and QTL Mapping. Also, the problems of construction of molecular genetic map were discussed. Firstly, polyploidy of sweet potato is not clear yet, and karyotype information is limited曰Secondly, the type and amount of molecular marker are both limited, especially those based on specific fragment loci such as SSR and EST-SSR, and those based on disease resistance gene homologous sequences; Thirdly, the Molecular marker genetic maps up till now have not met the requirement of practicability yet;Fourthly, small mapping group of F1 progeny restricts the construction of fine genetic map, and the accuracy of QTL;Finally, the aspects need to be improved are also pointed out.