Taking economic income, social exclusion and separating cost as influencing factors, this paper builds a Migration Utility Function, to illustrate comprehensive strategic migration decision model of four different migration patterns. An empirical case study of Cixi City in Zhejiang Province, China, shows that the economic, social and psychological aspects are key factors when choosing a migrating pattern. Besides, Non-permanent migration is a rational choice response to balancing the migration utility function. It is not qualified to form conditions for family permanent migration at this stage. In such case, only a matter of household registry reform could not change the tendency of non-permanent migration.