The new mini watermelon F_l hybrid‘Sumi No.8’is developed by crossing SW032 as female parent and SW058-1 as male parent. It is of early maturity. It takes 30 days from pollination to maturity. Its growth vigor is moderate. It is tolerant to low temperature and weak light with high capacity for setting fruits. The fruit is oval. The single fruit weight is 1.8-2.3 kg. The rind is light green，covered with dark green narrow strips.The pericarp thickness is 0.4-0.5 cm. Its flesh is yellow and tastes crispy. The center soluble solid content is 11.0%-12.2%. The fruit is juicy with less fiber and good flavor. It can yield 30.0-37.5 t·hm^-2. It is suitable to be cultivated in middle and lower valley of the Yangtze River in spring in plastic tunnel.