Abstract: Creep tests of BSTMUF601 superalloy for elevated temperature have been carried out under different temperature and stress. The creep deformation characteristic of BSTMUF601 superalloy was investigated based on the creep curves. And then, a creep constitutive model for elevated temperature was proposed by introducing a modified θ projection method, which contains three stages of creep. The predicted results by using the model are in good agreement with the experimental results. The average relative error of the model fitted is 1.86%. Compared with the model ignored the second stage of creep and the model ignored the first stage of creep, the average relative error was reduced 0.1% and 6.02% respectively. It is indicated that the model will be a wider range of application whereas the prediction precision is not reduced. Dislocation structure and its distribution for creep specimens and void evolution for creep rupture specimens have been carried by analyzing the microscopic structure. The results show that: the creep stress index was close to 5 during the steady-state creep stage for different temperatures. The dislocation climb mechanism controlled the creep deformation process. There was no stacking fault or microtwin observed in phase or matrix. Cracks originate from the cavities at grain boundary and along the boundary, which led to fracture. Grain boundary fracture is the main creep rupture mechanism.