Hollow nanospheres can be synthesiszed by template-free sol-gel method. Based on sol-gel approach, Biological and Medical Nanotechnology Group of South East University has prepared Fe3O4 hollow nanospheres by adding GA solution which is an easy and convenient and a self-assembled method without any external template. By this method, the reaction time is shorter than the one by the other available methods. The sol-gel process is intensively subjected to the concentration of the added GA (glutamic acid). It was found that the Fe3O4 hollow nanospheres could be obtained when the concentration of the added GA stayed in a certain range. Besides GA, other amino acids such as leucine could be employed to fabricate the Fe3O4 hollow nanospheres. Due to the novel structure and other properties of Fe3O4 the hollow nanospheres, they have the potential applications in magnetics, catalysis, drug-delivery carriers and also could be applied to the synthesis of other composite core-shell nanostructures and chemical reactors.