In this paper, we propose two four-base related 2D curves of DNA primary sequences and their corresponding single-base related 2D curves. The constructions of these graphical curves are based on the assignments of individual base to four different sinusoidal functions; then by connecting all these points on these four sinusoidal functions, we can get the F-B curves; similarly, by connecting the points on each of the four sinusoidal functions, we get the single-base related 2D curves. The proposed 2D curves are (...) all strictly non degenerate. Then, a 8-component characteristic vector is constructed to compare similarity among DNA sequences from different species based on a normalized geometrical centers of the proposed curves. As examples, we examine similarity among the coding sequences of the first exon of beta-globin gene from eleven species, similarity of cDNA sequences of beta-globin gene from eight species, and similarity of the whole mitochondrial genomes of 18 eutherian mammals. The experimental results well demonstrate the effectiveness of the proposed method. (shrink)