Brassica juncea is one of the economically important plants, well known because of its medicinal and nutritive values. DNA barcoding technology has been used successfully in past years for species identification and phylogenetic construction. Thus, the present work was planned to study the divergence amongst 15 species of Brassica juncea through construction of phylogenetic tree using computational approach. Here, DNA barcoding genes such as ITS, rbcL and trnH-psbA of Brassica juncea were selected for tree construction using bioinformatics tools and techniques. Further, biogeographical study of Brassica juncea were performed for fourteen countries and continents using RASP, which resulted the world wide distribution as well as advocated for the origin of few subspecies of Brassica juncea from china and Asia. Thus, this work would throw lights on further genetic evaluation study of Brassica juncea.