In view of the characteristics of large internal back arc transition curvature and bending and torsion of autonomous nuclear power hollow blades in CAP1400,its internal back arc forming mold and thermoforming technology are key to ensure the manufacturing accuracy of the blade. According to the structural characteristics of the internal back arc profile,a reasonable thermoforming mold is designed by using the finite element simulation analysis. The thermophysical performance result of JMatPro is simulated and analyzed with Autoform by thermodynamic coupling, and a reasonable hot pressure technology for internal back arc forming is finally worked out to realize the forming of complex multi-dimensional hollow blades and ensure the manufacturing accuracy of nuclear power hollow blades.