DNA is a nucleotide acid in form of double helix which contains genetic instruction to determine biology development of all forms of cell's life also it relates with genetic characteristic inheritance. In this research, we will see the similarity of two DNA sequences. DNA sequences that we used are human, orangutan, and gorilla. The method that we used to analyze the similarity of DNA sequences is Graph Theory. This method started by modeling each DNA sequence into a graph, making its adjacency matrix and builds a matrix vector for each graph. From these vectors we will determine similarity of two DNA sequences. The similarity of DNA sequences is determined by the similarity level using Cosine, Correlation, and Euclid. Where, the results are shown by the smaller distance, and then showing the similarity of two DNA sequences. And then compare the result from Graph Theory with the results of Basic Local Alignment Search Tools (BLAST) program. Finally, the result of research shows that Human and Gorila have close similarity of their DNA sequences. 2010 Mathematics Subject Classification: 00A69.