The work is devoted to the Heusler alloys as a candidate for applications in spintronics. On the basis of experimental studies the electronic structures of these alloys by computer simulations were carried out to explain the structural and electronic properties of the Ni2MnGa and Co2MnGa compounds by using state-of-the-art computational ab-initio methods. The total energy calculations for the cubic structures, band structure and their nature and magnetizability of the compounds are investigated. The obtained results explained the dependence of the magnetic properties of the alloys on the geometrical structure as well influence of Co and Ni atoms.