Based on ecological value of each ecological environment water requirement functions, this paper proposed that it should classify water requirement priorities of the ecological water requirement type to meet the character of water shortage in arid region. According to this theory, with studied on Minqin Basin ecological problems, it planned the principle of water requirement of every ecological environment type. Then after determined the priorities to every type, this paper suggested that the current problem is to meet the water requirement of the sand shifting control forests living at the edge of oasis and the grounder water level rising in basin. And calculated these two types′ water demands quantity was 1.4682×108m3, which the living of sand shifting control forest demand 1.077×108m3, the recovery of artificial recharge groundwater demand 03912×108m3.And compared with the relevant research results finally, it pointed that this calculation results was reasonable.