In this article we will study the structural, elastic, electronic and magnetic properties of new Ti2-based Heulser alloys Ti2NiX(X = Al, Ga and In), using ab initio electronic structure calculations. The results show that these compounds exhibit a halfmetallicbehavior. The full-Heusler alloys show a Slater-Pauling behavior and the total spin magnetic moment per unit cell(Mt) following the rule Mt=Zt-24. The origins of the gap in these half-metallic alloys are well understood. It is found that thehalf-metallic properties of Ti2-based compounds are insensitive to the lattice distortion and a fully spin polarization can beobtained within a wide range of lattice parameters. Calculations of the total magnetic moment is 3.00 mB for a wide range ofmesh. Our results suggest that Ti2NiX (X = Al, Ga and In) are promising materials for spintronics applications in the futureThis is favorable in practical application.