Abstract: Involving a new idea of azimuthal partition in a symmetric magnetically insulated transmission line oscillator(MILO), an model of L-band bifrequency MILO(BFMILO) is put forward in this paper. By numerical analysis, dispersion curves of BFMILO are obtained. The resonators of BFMILO with closed boundary and open boundary are investigated, the parameters such as eigen-mode frequency, field distribution, Q-value, etc. are obtained. The investigation shows that, the structure of BFMILO can independently resonate in particular partitions, and each partition corresponds to a particular frequency. Thus the investigation proves the feasibility in the sight of high frequency characteristics that a BFMILO can generate high power microwave with two stable frequencies.