Optimal condition, stability and Km of phytase which was from Aspergillus oryzae093 were studied. The optimal temperature and pH for sodium-phytate hydrolysis by Aspergillus oryzae093 phytase is 50°C and 5.5 respectively. Phytase has better heat stability as temperature below 45°C. The phytase activity remained 90% when pH is 5.0 to 6.0. Low concentration Fe2+ and Mg2+ can promote phytase activity, while Cu2+, Mn2+, Fe3+, Al3+ or high concentration Fe2+ and Mg2+ can inhibite the activity of phytase. The Km is about 4.8×10-5 mol•L-1 when sodium phytate as substrate. The enzyme properties of Aspergillus oryzae093 phytase make it could apply to food and feed to reduce the phosphorus exhausted to environment.