A simple and reliable DNA extraction method for dry seeds of Brassica napus has been developed in our laboratory. The NaCl and PVP were used to remove polysaccharides and polyphenols during DNA purification. The oil and proteins of dry seeds were removed only through centrifugation in this method. The RAPD amplification patterns have no obviously difference between the DNA extracted from dry seeds and fresh leaves extracted with control method. The good results of SSR molecular markers on the DNA of dry seeds of another 12 B. napus indicating that the DNA extracted from dry seeds was freedom from common contaminating compounds. In conclusion, this method could be widely used in DNA extraction from dry seeds of B. napus.