To investigate the codon usage bias (CUB) and its influencing factors in the chloroplast genome of Styphnolobium japonicum f. oligophyllum, we sequenced, assembled and annotated the genome using Illumina high-throughput sequencing, and systematically analyzed 52 protein-coding sequences. The chloroplast genome is 158,837 bp with a typical quadripartite structure, containing 129 functional genes. It presents a mean GC3 content of 28.26% and a mean ENC value of 45.40, indicating weak CUB and low gene expression. Among 31 preferred codons (RSCU > 1), 29 (93.5%) end with A/U. Neutrality plot, ENC-plot and PR2-plot analyses reveal that natural selection is the primary regulator of CUB. A total of 19 optimal codons were identified. These results provide fundamental data for the genetic engineering of S. japonicum f. oligophyllum.