Studying the deformation and microstructure evolution for Ni-based single crystal alloys at high temperature has important effects on the design of turbine blades and disks. However, in-situ high temperature tests under scanning environment pose an important challenge for the current experimental conditions. In this paper, the resistance heating system was introduced in the high temperature fatigue experimental apparatus. The in-situ tensile test of 900°C was successfully carried out. The experimental results showed that the crack initiation was mainly caused by inclusion debonding. The fracture mode was mainly characterized by the connection of micro holes.