Abstract:Twelve species in the genus Nitraria around the world are verified and revised through literatural studies. The phylogeny in the genus is touched based on the structure of pericarp and its evolutionary trend,pollen morphology,and distribution pattern of different species. A classification system of the genus is proposed. The key to sections and species in the genus is achieved .The distribution maps both in China and the world are provided in the present paper according to gegraphic distribution of the genus.