The invention discloses a surface treatment method for improving the welding properties of Si3N4 ceramic and gamma-TiAl alloy. The method comprises the following steps: (1), preparing nickel alloy layer on the surface of the gamma-TiAl alloy from a Ni-Ti alloy target material by adopting a double glow plasma surface metallurgy method, wherein the nickel alloy layer comprises a nickel deposition layer and an inter-diffused layer; (2), injecting Ti ions on the surface of the Si3N4 ceramic through an ion injection method, so as to treat the surface of the Si3N4 ceramic; and (3), welding the gamma-TiAl alloy treated through the double glow plasma surface metallurgy method in the first step and the Si3N4 ceramic subjected to surface treatment in the second step in vacuum diffusion welding equipment. According to the method, the nickel alloy layer is prepared on the surface of the gamma-TiAl alloy, the Ti ions are injected to the surface of the Si3N4 ceramic through the ion injection method,and the vacuum diffusion welding between the Si3N4 ceramic and the gamma-TiAl alloy can be directly realized. The method is high in efficiency, and can greatly improve the application of vacuum diffusion welding to the welding technology of the Si3N4 ceramic and the gamma-TiAl alloy.