In this work, the effect of varying Al and Ti contents of Incoloy825 alloy on the phase transformations that might occur in the material was simulated using a thermodynamic modelling tool. Employ optical microscope (OM), scanning electron microscope (SEM) to observe the microstructure as well as the corrosion morphology of the tested alloy. Potentiodynamic polarization curves, electrochemical impedance spectroscopy and corrosion rate of the tested alloy were investigated by electrochemical workstation and static weight-loss method in 1mol/L, 3mol/L HCl solutions. The results indicate that the microstructure of as-forged Incoloy825 is composed of γ substrate and a small quantity of Ti(C,N) at final forging temperature. With the improvement of Al, Ti contents, precipitation volume of blocky Ti(C,N) increased gradually, grain is refined; corrosion current density increased gradually, corrosion resistance decreased significantly, tendency to pitting of the tested alloy is increased. Large, faceted Ti(C,N) particles in Incoloy825 alloy provide preferred sites for pit initiation in the chloride environments. With the improvement of Al, Ti contents, corrosion products on the tested alloy surface became more porous, the protection to matrix is decreased.