The surface of TiAl alloy is nitrided by CO 2 laser gaseous alloying with nitrogen. The experimental result shows that the nitrided layer consists of TiN and TiAl phases. Dendrite TiN distributes in the nitrided zone homogeneously. The cross section micro hardness of the material changes continuously. The nitriding level increased with the reaction time increasing. The higher laser energy density, the deeper nitrided layers. The depth of the nitrided layer and the surface micro hardness are 200 μm and HV700 as laser power density of 3.35×10 5W×cm-2, scanning velocity of 300 mm×min-1, and nitrogen pressure of 0.35 MPa are used. Under the same experimental conditions, the nitriding level and the depth of the nitrided zone of TiAl alloy are lower than those of titanium.