Hausmannite Mn3O4 nanoparticles were successfully prepared via a facile one-step solvothermal route with Mn(CH3COO)2·4H2O as manganese source in the mixed solvent of acetone and water.Powder X-ray diffraction(XRD),Fourier transform infrared(FTIR) spectrometry and transmission electron microscopy(TEM) were used to characterize Mn3O4 nanoparticles.It was found that the particle size could be tailored by varying the synthesis temperature.On the whole,the particle size becomes larger with the rising of solvothermal reaction temperature.But there is no linear relation between them.According to the different temperatures(60―140 °C),the average particle size is from about 9 nm to 15 nm.Magnetic properties of Mn3O4 samples prepared at 60,100 and 140 °C were studied via a superconducting quantum interference device(SQUID),respectively. Hausmannite Mn3O4 nanoparticles were successfully prepared via a facile one-step solvothermal route with Mn (CH3COO) 2.4H2O as manganese source in the mixed solvent of acetone and water. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrometry and transmission electron microscopy (TEM) were used to characterize Mn3O4 nanoparticles. It was found that the particle size could be tailored by varying the synthesis temperature. On the whole, the particle size becomes larger with the rising of solvothermal reaction temperature. no linear relation between them. Based on the different temperatures (60-140 ° C), the average particle size is from about 9 nm to 15 nm. Magnetic properties of Mn3O4 samples prepared at 60,100 and 140 ° C were studied via a superconducting quantum interference device (SQUID), respectively.