The Sylheti Bangla, a variety of Bangla language is primarily spoken in the Sylhet District of Bangladesh, Barak Valley of Assam, Tripura, especially in North Tripura. The systematic perusal on English spoken by Sylheti Bangla speakers demonstrates that it carries a huge difference with English (RP) specially in respect to pronunciation, syllable structure, stress, intonation. The disparities between Sylheti English and English (RP) are because of a number of divergent variances between Sylheti Bangla and English which often makes the acquisition of English an arduous job for the Sylheti speakers. The errors committed by Sylheti speakers during their speaking in English can be attributed to the interference of the rule of mother tongue in learning the second language. This interference can be of phonological, morphological and sentence structure. However, the domain of this paper is exclusive to phonological interference of L1 on L2 through the contrastive analysis of the phonological aspects of Sylheti Bangla and English (RP). This paper intends to improve the status of English teaching-learning process compared to contemporary practices. Thus, it aspires to contribute to the theory of second language acquisition with a particular focus on learning English by the Sylheti speakers.