In trying to solve constrained optimization problems using genetic algorithms, the method to handle the constraints is the key factor to success. In this paper, some features of GA (genetic algorithms) and a large class of constrained optimization problems are taken into account and a new method called Fixed Proportion and Direct Comparison (FPDC) is proposed, which combines direct comparison method and the strategy to keep a fixed proportion of infeasible individuals. It has been successfully integrated with the ordinary GA. Numerical results show that it is a general, effective and robust method.