The best method of decision model selection is based on fully understanding the meanings of decision problem
and the capacities of decision model. Through domain ontology, decision problem and decision model are described in form of formal semantics which can be understood automatically by computer. Due to the understanding semantics of decision problem, DSS can extract the requirement of problem and select the corresponding model class which can solve the problem. Then, the capacities of candidate models are evaluated according to the semantics of decision models and eventually find out decision model which is the most completive one for the problem. Finally, the example analyzing and experiment show that the model selection method is effective and feasible.