Environmental migration has several important factors.

(1) The total population exceeds the overloaded area of population environmental capacity, which is the fundamental reason of environmental migration, mainly manifested in the lack of food and water resources, poor sanitation and poor living conditions;

(2) The areas with large population and unsaturated population make environmental migration possible;

(3) The will of immigrants (including the meaning of being forced to realize by compulsory means) enables environmental immigration to be realized.