The magnetic shape memory alloys (MSMAs) have both martensitic transformation and ferromagnetism in the same material, thus external magnetic field can be used to induce/control the phase transformation or the reorientation of martensite variant. MSMAs have received considerable attention for their interesting properties and wide applications in different fields. For practical applications, the martensitic transformation temperature T_M is an important factor and a high T_M is preferable. Recently, Zn-doping has been found to be a possible way to elevate the value of T_M of Ni-Mn based MSMA, but this effect on other kinds of MSMAs is not very clear yet. Heusler alloy Ni₂FeGa is a typical MSMA with unique properties, however, its T_M is relatively low. So it can be meaningful to find possible ways to increase its phase transition temperature. In this paper, the influences of Zn-doping on the electronic structure, martensitic transformation and magnetic properties of Heusler-type magnetic shape memory alloy Ni₂FeGa are investigated by first-principle calculations. Total energy calculation and charge density difference indicate that Zn atom prefers to occupy the Ga (D) site when substituting for Ga in Ni₂FeGa_1–xZn_x (x = 0, 0.25, 0.5, 0.75, 1). This main-group-element-like behavior is related to the closed 3d shell of Zn. Due to the similar atomic radii of Ga and Zn, Zn-doping does not lead the lattice constant to change greatly. The variation of the energy difference ΔE_M between the martensite and austenite with Zn content increasing is calculated, and the result shows that ΔE_M increases with Zn-doping increasing, and thus conducing to increasing the stability of the martensite phase and to evaluating the transformation temperature T_M in Ni₂FeGa_1–xZn_x. This trend can be explained by the Jahn-Teller effect observed in the DOS structure. The Zn-doping does not change the magnetic structure of Ni₂FeGa. A ferromagnetic coupling between Fe spin moment and Ni spin moment can be observed within the whole range studied. The calculated total spin moment increases with Zn content increasing. The variation of formation energy E_f with Zn-doping is investigated. In Ni₂FeGa_1–xZn_x a negative E_f is retained within the whole range studied, though it increases slightly with the doping of Zn. It is also found that the Zn-doping can increase the stability of L2₁ Heusler phase in Ni₂FeGa_1–xZn_x and suppress the formation of the FCC L1₂ phase.