Ni-Cr-Al superalloys are widely used as sealing materials in new type aero-engines. Though Cr and Al contents can improve the resistance of high temperature oxidation and hot corrosion, it can affect the hot workability of alloys at the same time. The effects of Cr and Al contents (Cr, 15%-25%; Al, 4%-5%, mass fraction) on the hot workability were studied by isothermal compressive deformation at deformation temperatures of 1000 oC to 1200 oC and strain rates of 0.1, 1, 5 and 20 s-1. The results indicate that increasing of Cr or Al content can reduce the safe region of hot working to different extents. Equilibrium phase diagrams and microstructure observation show that the effects of Cr and Al contents on hot workability is mainly caused by the morphology and fraction differences of cellular carbide in grain boundary. Considering the hot workability, microstructure change and corrosion resistance at high temperature, it is concluded that 20%Cr and 4%Al is the best component for sealing materials of Ni based superalloys.