Because of the low density, high specific strength and excellent performance at high temperature, γ-TiAl based alloys have become a new generation of materials in the aeronautic field. However, its poor ductility at room temperature leads to its bad performance in the manufacture process, which has set a boundary to its wide applications. In this paper, 16 La and (or) Zr doped γ-TiAl systems (S1, S2, S3, S4, S51~S55, S61~S65, S7 and S8) are constructed and investigated by using the plane wave pseudo potentials method based on the density functional theory and other physical theories. The results of average formation energy show that they possess good energy stabilities. According to the elastic parameters and Born-Huang criteria, it is forecasted that they (except system S61) are in good mechanical stabilities. So, the 15 doped systems can be prepared in experiment and are stable in existence. The comparison of G/B shows that all La and Zr co-doped systems (especially S51, S52, S63 and S64) have better ductile properties than that of pure γ-TiAl systems. The ductility of co-doped systems is not much correlated with comparative position of doping atoms. The calculation results and discussion about population, charge densities indicate that the improvements of ductility and isotropy of co-doped systems come of the decrease of Ti4s→3d, Al3s→3p charge transfer and increase of free electrons number. This change results in the weakening of p-d orbital hybrid, the decreasing number of bonds Al (La, Zr)-Ti and the increasing strength of covalent bond Ti-Ti, and then the chemical bonds Al-Al, Ti-Ti and Al-Ti distinctly tend towards the same strength and become stronger metallic property.