This paper reveals a novel magneto-optic recording characteristic of Indium Bismuth Calcium Vitriol Iron Garnet (In-BiCaVIG) crystals in high power microwave (HPM) field. The initial state of magneto-optic rotation in the In-BiCaVIG crystal changes under about 100 MW HPM pulse, 2～10 GHz in frequency and about 50 ns in width. The changing values of magneto-optic rotation are related to the peak intensities of magnetic field in the direction of optical path. The changed directions of magneto-optic rotation are related to the initial states of crystals. The changing magneto-optic rotations related to the HPM magnetic field can maintain in the crystal for several days or more unless being erased by a magnetostatic field.