Transgenic oilseed rape Brassica napus, one of the first genetically modified crops, has now been released to commercial use in Canada and Australia. As a cross-pollinating crop, its natural crossing rate is 30%, and it is liable to cross with other Brassica species. The ecological risk of transgenic oilseed rape has been concerned by the scientists all over the world. There are two ways for the pollens flow of transgenic oilseed rape, one takes place between transgenic oilseed rape and other related wild species, and the other occurs between transgenic and nontransgenic oilseed rape. The gene may flow to other related wild species, but it is unlikely to get hybrids in field. Because the gene can really flow to the conventional oilseed rape, it is necessary to have a sufficient isolation distance in cultivating transgenic oilseed rape.