A dynamic model with the consideration of environmental fluctuations for predator-prey systems is developed. Evolvement curves and phase diagrams are obtained from the model. The system evolvement with and without environmental fluctuations is discussed and compared. The modeling results show that environmental fluctuations may induce species evolution and bring new species into the predator-prey system. Our study strongly suggests that the model can significantly improve the description of predator-prey system dynamics by considering the influence of environmental fluctuations.