SrTiO3 powders with different particle sizes from 50 to 100 nm have been hydrothermally prepared from different Ti and Sr precursors and characterized with XRD, TEM, and other techniques. The effects of strontium and titanium precursors on the formation of SrTiO3 powders and the reaction conditions such as alkali concentration were studied. Furthermore. the effects of precursors on SrTiO3 particle size have been studied in detail.