‘Longke No.2’ is a new watermelon F1 hybrid of mid-early maturity，bred by crossing inbred lines ‘08C41’ as female parent and‘ 08C44’ as male parent．Its whole growth period in open field is about 90 days and 109 days under plastic shed．The fruit development periods under these 2 cultivation conditions are about 30 days and 35 days，respectively．The plant grows healthily and branches moderately．It is easy to set fruit．The first female flower of main vine sets on 5-7th node．The next female flower appears on every 3-4 sections．Its fruit is of round shape and the green peel covered with dark green stripes．Its peel is 0.9 cm in thickness and tolerant to storage and transportation．The flesh is bright red in color，crisp，juicy with good flavor．The central soluble solid content is 12.4% with smaller sugar gradient between fruit center and edge．The single fruit weight is about 3.6 kg and average yield is 64.05 t·hm-2．It is suitable for cultivation in Gansu Province and areas with similar ecological conditions in open fields or greenhouse in spring．