The complete mitochondrial genome of Siberian sturgeon Acipenser baerii had been determined. The total length of the mitogenome was 16,763 bp and had 13 protein-coding, 22 tRNA, and 2 rRNA genes. Except for the eight tRNA and Nd6 genes, all other mitochondrial genes are encoded on the heavy strand. The overall base composition of the heavy strand is 30.3% A, 24.3% T, 29.1% C, 16.3% G, with an AT content of 54.6%. The DNA sequence of A. baerii shared 97.8, 97.6, 93.5, 91.6, 93.6, and 87.1% sequence homology with that of Acipenser sinensis, Acipenser gueldenstaedtii, Acipenser transmontanus, Acipenser dabryanus, Acipenser stellatus, and Polyodon spathula. Molecular data presented here provide a useful tool for evolutionary as well as population genetics studied.