Abstract: A novel global optimal designing approach called particle swarm optimization(PSO) is proposed for designing the broadband matching network of a antenna.The problem due to the aberration of value of a lumped component in UHF frequency band is solved by using equivalent impedance.Finally,based on the method above,a broadband matching network for an omnidirectional ultra-wide band miniature antenna,with VSWR<3.0 in 30~512MHz,is designed and manufactured,and the calculated results are in good agreement with the experimental results.