Effect of Fe on the martensitic transformation of NbRu high-temperature shape memory alloys is investigated by the experiments and first-principles caIculations. The results show that Fe is predicted to occupy Ru sites. The addition of Fe increases the stability of Nb50Ru50-xFex β phase, leading to the significant decrease of the β to β1 martensitic transformation temperature. In addition, the mechanism of the Fe alloying effect is explained on the basis of the electronic structure.