The forging load of super large turbine disc with a diameter over 2 m may approach or even surpass the limit of 800 MN of the largest press machine in China, which is the extreme manufacturing. Thus, maintaining good mechanical properties and controlling forging load are two key factors during the forging process of super large turbine disc. 25 groups of forging parameters was designed based on Taguchi method. The multi-objective optimization of finite element method simulation results was conducted by SNR and ANOVA methods. Results show that the most uniform and refined recrystallization microstructures are obtained under optimal forging load. The optimal combination of process parameters is determined under extreme manufacturing condition: temperature=1120 °C, strain rate=0.06 s^-1, pre-forging size=985/610/475 mm, and die temperature=280 °C. The order of importance of each parameter to the simulation results is as follows: temperature>strain rate>billet shape>>die temperature. The experimental results obtained under the optimal parameters combination show good agreement with the simulated results, which demonstrates that this approach may be used to manage the load and microstructure of super large forgings while avoiding a significant number of experiments and numerical simulations.