Abstract: Single crystal Bi and Gd substituted YIG films were prepared by liquid phase epitaxy method, and their microwave and magneto-optical properties were studied. The results show that the crystal quality of the sample is good, and the average surface roughness is 0.4 nm. The special saturation magnetization is 25 emu/g, and the saturation external magnetic field is about 650 Oe. In the range of 0-20 GHz, the Ferromagnetic Resonance Linewidth ΔH is less than 8 Oe, and the frequency is linear with the linewidth ΔH. At the wavelength of 1550 nm, the specific Faraday rotation angle of saturation state is about 0.1 (°)/μm, and the Faraday rotation of ±45° can be achieved with the superposition of two pieces of films. At 1550 nm, the transmittance is close to 90% and the absorption coefficient is lower than 16 cm⁻¹. It has important application value in infrared magneto-optic and microwave communication.