Objective To establish a mouse aplastic anemia model by using cyclophosphamide and methylbenzene, and research its pathomorphology. Method Cyclophosphamide 50.0mg/kg was injected each other day, four times,with inhalation of toluene (30mg/L, 2h/d for 8 days) to reproduce aplastic anemia model. Control group was injected with equivalent saline subcutaneously without narcotics. Result The peripheral hemogram of mice in the model groups showed that there was a remarkable decrease in three types of cells (p<0.01) and in bone marrow hyperplasia. And there was a distinct increase in lipocytes. The spleen was atrophied, and its lymphnodule became small or disappeared. The microcirculation of ear was obstructed. All indices conformed to aplastic anemia. After 35 days, the pathological changes still existed. The changes were similar to human aplastic anemia, while there wasn't such changes in the control group. Conclusion The method to reproduce aplastic anemia model was simple, and had a high success rate. It could be used to screen relative drugs.