Antennas optimization design using numerical algorithm is important in modern antennas research. An automatic optimization approach of antenna design based on differential evolution strategy (DE), though externally calling the solver of electromagnetic simulation software, is developed in this paper. In order to demonstrate the effectiveness and the feasibility of this method, an ultrawideband microstrip patch antenna was designed and optimized. The simulated results show that the designed antenna is applicable in UWB system, with impedance bandwidth(S11<-10 dB) from 3.18 GHz to 13.185 GHz and percentage bandwidth up to 62.7%. Meanwhile, Omni-directional characteristics in H-plane and high gain performance are achieved. The approach establishes a foundation for application in parallel computation technology to improve the efficiency of optimization.