Uniform hematite microstructures can be prepared by a hydrothermal method by the use of ascorbic acid in an ethanol/water solvent mixture. At the same time, a reasonable mechanism for the growth of hematite microstructures has been proposed. The blocking temperature of hematite microflowers is ca. 80K with an external field of 100Oe, and above which they display superparamagnetic performance at room temperature. This synthesis approach is expected to become an appropriate method for the preparation of other uniform microstructure of metal oxide.