High temperature alloy due to its excellent comprehensive high temperature performance is used in the manufacture of hot end parts of aircraft engines, gas turbines, etc., with the increasing requirements of equipment design for material service temperature, the comprehensive performance requirements of high temperature alloys are becoming more and more stringent, and modified alloys with better performance are constantly born. Taking the modified alloy DZ411G for largesize oriented cylindrical hollow blades of a new type of heavy-duty gas turbine in China as the research object, this paper analyzed the influence of C, Al, Ti, Cr, Ta and other elements on the initial precipitation temperature, maximum precipitation amount, solid-liquid phase line, γ/γ′ mismatch degree of the main alloy phases with the help of phase diagram calculation software JmatPro, and provided a basis for the optimization of chemical composition of DZ411G alloy, the design of smelting inlet point and the formulation of heat treatment process. According to the theoretical calculation results, a reasonable formula was formulated, and the industrial production of DZ411G alloy was completed for the first time.