In this study, the obtainment and sequence analysis of the cysteine synthase gene from banana (Musa acuminata L. AAA group cv. Brazilian) was conducted, and then its expression profiles in different organs and under the stress treatment were also carried out. Through RACE approaches and bioinformatics analysis, the full-length cDNA of the cysteine synthase gene, named as MaCSase, was obtained from root of banana cDNA library, and its sequence characters were also analyzed. The expression levels of MaCSase in different organs and the expression profiles of MaCSase in banana root under the exogenetic stresse were analyzed by Real-time qPCR. Sequence analysis showed that the full-length cDNA sequence of MaCSase was 1367 bp. MaCSase had a 1065 bp open reading frame in length encoding 355 amino acids. Compared with other plants, the homology of MaCSase was more than 79%. The amino acid identity compared with Oryza sativa, Medicago sativa, Allium sativum and Zea mays was 86%, 85%, 84%, 84% respectively. Organs specific analysis showed that MaCSase was constitutively expressed in roots, stems, leaves, flowers and fruits. The expression level was higher in stems. Analysis showed that the expression of MaCSase in the banana root was up-regulated with the increase of the processing time under the salt stress. It was strongly induced at the 6 h stress.