Usoi Tripura is a southern dialect of Tripura/Kokborok, which belongs to the Boro-Garo group of the Tibeto-Burman language family, and is spoken mainly in the Chittagong Hill Tracts of Bangladesh. In this paper, based on my own data, I have briefly described the phonology of the Usoi Tripura dialect. Thereafter, I have tried to compare Usoi Tripura forms with their corresponding Proto-Boro-Garo (PBG) forms found in the seminal work _ e Comparative Phonology of the Boro-Garo Languages by U. V. Joseph and Robbins Burling. My comparative work made it clear that Usoi Tripura is conservative in that it still retains the three-way contrast of stop initials and two types of liquids and tones, respectively, while it is innovative in that it has already done away with final liquids and replaced three types of final stops with glottal stops. Aside from these general tendencies, Usoi Tripura shows some peculiar characteristics such as the absence of voiced velar stops in native words and the voicing of PBG initial bilabial stops where their finals are liquids or dental stops in particular. Exhaustive lists of phonological correspondences between Usoi Tripura and Proto-Boro-Garo are also provided.