Composition dependence of martensitic transformations as well as the magnetic properties for the Ni2Mn1+xIn1-x (0.25 ≤ x ≤ 0.58) alloys were investigated by using the first-principles calculations.Key results demonstrate that the stability of parent austenite (A) decreases gradually with increasing Mn content whilst it is opposite for the martensitic phase.This causes the total energy difference between the austenite and martensite phases increscent with increasing Mn contents.When x =0.33,the marten-site transformation during cooling is PA→FA→NM.When x ≥ 0.42,an intermartensitic transformation occurs from modulated 6 M martensite to non-modulated (NM) martensite with the martensite trans-formation sequence of PA→ FA→6M→ NM.The martensitic transformation from austenite to martensite accompanies the transition from ferromagnetic to ferrimagnetic state.This is a typical magneto-structural coupling transformation.The analysis of the density of states demonstrates that the Ni 3d state plays an important role in the phase stability.