Dietary composition and selection of food items are important approaches for the flexibility and adaptability of macaques in different natural habitats. With a wide distribution range, Assamese Macaques feed on various food types. This study reports the consumption of 57 plant species from 30 families. A total of 2,233 scans resulted in 16,381 feeding behavioral records during the study period from 2018 to 2020. Macaques appear to be primarily folivorous in Dampa as leaves (young & mature) constitute 44.74% of their daily dietary intake while the fruit consumption was found to be 25.31% of the total dietary intake. Plant species like Artocarpus lakoocha (15.65%), Albizia procera (12.03%), Glochidion hyneanum (10.53%), Diospyros glandulosa (9.49%), and Albizia lebbeck (7.28%) contributed significantly to macaque’s diet compare to other plants. No significant variation was observed on time spent for feeding on leaves, fruits, flowers, and seeds in both different months and seasons of the year. The highest percentage of the diurnal time invested on feeding activity was (59.04%) in the month of January (winter season), which may be due to the cold climate and scarcity of proper feeding items and the least was (35.19%) in June where food resources are more readily available. The richness of fruiting plants in Dampa Tiger Reserve appears to fulfill the dietary requirement of Assamese Macaque and therefore intactness of forest resources is necessary for their development and conservation.