This paper focuses on methods of optimizing a single classifier and combining multiple classifiers by genetic algorithms (GA). The method uses the strategies of stacking. There are two steps in classical strategies of stacking, and GA is used as the second step in the method. Experimental results show that it performs well on the task of optimization. Comparing with the single algorithm, it enhances the precision. In task of combiningoptimization, it can obtain more understandable result than constituent learners.