The present paper aims to discuss the geographical distribution of the Arenaria L．on the basis of the unity of phylogeny and process of dispersal in plants．There are 306  species of Arenaria in the world，belonging to 10 subgenera and 24 sections．Arenaria are mainly distributed in Eurasia，America and northern Africa．According to the geographical elements of Arenaria in the world，eight geographical distribution pattern and 11 variants are divided．  According to Takhtajan‘s and Wu‘s view points of phytochoria，the number of species is counted for each region，which shows clearly that the Mediterranean，W．Asia to northwest C．  Asia region and Hengduan Mountains to Qinghai-Xizang(Tibet)Plateau region of China have greatest numbers of subgenera and species．There are six subgenera and 105 species in China，and especially its southwest part，Xizang(Tibet) ，Yunnan and Sichuan，is richest in subgenera and species．According to Lu‘s view point of centre of floristic region，it is determined by the following two principles：(a)A large number of species concentrate in a district，namely the centre of frequency；  (b)species of a district can reflect the main stages of the systematic evolution of Arenaria，namely the centre of diversity．It is clear that the Mediterranean，W．Asia to nothwest C．Asia region form the main distribution centre of Arenaria，while the Hengduan Mountaons to Qinghai-Xizang(Tibet)Plateau Region form the secondary distribution centre．On the basis of separation time of the South American continent from the African continent，the origin of Arenaria might date back to the Middle Cretaceaus．After the emergence of Arenaria plant on earth，it first developed and dispered in northern Mediterranean．During the period of its origin and development，Arenaria rapidly developed and dispered to North Africa，Cental America to South America and from Eurasia to North America by three routes：the Mediterranean-North Africa-Central America-South America route，Europe-Greenland-North America route and  Asia-Bering Bridge-North America route．Finally，the formation of the modern distribution