A method and an apparatus for determining variable dependency are disclosed. In the present invention, a variable dependency is determined in advance arbitrarily; partial variables are selected from the current variable dependency, and a legitimate superior variable set is re-selected for each of the partial variables, and the new variable dependency is stored only if it meets the criterion of acceptance; when the termination criterion for establishing variable dependency is met, the optimal variable dependency is determined from all variable dependencies. Because the existing variable dependency is not taken as a reference when the new variable dependency is created, the new variable dependency is not misled by the existing variable dependency, and the time for finding the globally optimal variable dependency can be shortened.