SSR （simple sequence repeats） is a simple, tandem repeated several nucleotide sequence motifs. SSR is widely distributed over the genome of eukaryote. SSR is very usually as genetic marker because it contains plenty of information, covers the whole genome, co-dominant heredity, and is easily detected by PCR. Types of SSR, progress in studies, and its application in identification of varieties, genetic mapping and marker-assisted selection were briefly reviewed in the paper.