Using a twodimension fully electromagnetic ParticleinCell(PIC) simulation，the relativistic magnetically insulated transmission line oscillator (ＭILO) designed by Phillips laboratory is studied. A power output of about 1.5GW at 1.1GHz can be generated with this source when input voltage is 500kV and input current is 60kA. In addition we have researched the effect of changing the parameter of MILO on the work performance of MILO is researched．