Abstract: The spring diet of Hoolock Gibbons (Hoolock hoolock) was observed by tracking them at Nankang of Mt. Gaoligong from March 3rd to April 14th, 2007. Their feeding behavior could be divided into eating fruit, drinking juice and eating leaves. Feeding behavior, food species, part of food to be eaten and feeding sites of the gibbons were recorded by scanning samples. In their active regions, nineteen used plots (20 m×20 m) around the feeding tree as well as the same number of available plots by random sample were set. Data of six factors involving feeding tree and food resource were collected from the plots. Food species and their quantity, selective index and selectivity of feeding spots were calculated. The results showed that in spring at Nankang the gibbons ate 10 botanic species, three of them for fruits, one for juice and six for young leaves. Among 10 food species, only fruits of Schima khasiana and young leaves of Maglietia haokeri were under selected and the other eight species were over selected. The result of a Mann-Whitney U test showed that the food resource and food species were significantly different between the used and available plots. There were more food resources and food species in the used plots. Fruits were the main food resource of the gibbons in spring at Nankang and young leaves were the supplement. The over selected food was not always at a high feeding frequency; in contrast, the food with a high feeding frequency was not always the over selected food resource. The gibbons often selected fruits that could be eaten easily and young leaves containing less ash. The fruit was also the main water resource. Hoolock Gibbons usually chose regions full in food resources and food species, so they could spend less energy looking for food, and at the same time choose from several species which satisfied their nutritional needs.