Temperature field numerical simulation about he heat treatment process curve of large turbine rotor is presented. With simulation software Deform3D in according to the heat treatment pro- cessing of China First Heavy Machinery, the details of temperature change at the different loca- tion of the rotor is to be found. Once knowing the temperature field change, the duplex grain defect long time existed in large forgings can be solved with a quantitative analysis instead of only the qualitative one. Precondition for small metal samples is brought to simulate microstruc- ture and grain size change of large rotor according to the numerical simulation result. Also, con- sistent feature with real manufacture is showed from the physical experiment, so that the simula- tion can be used to not only improve the products process but also prevent wasting unnecessary energy and shorten process periods. The rotor quality is controlled thoroughly with plenty of ex- periments data. Temperature field numerical simulation about he heat treatment process curve of large turbine rotor is presented. With simulation software Deform3D in according to the heat treatment pro- cessing of China First Heavy Machinery, the details of temperature change at the different loca- tion of the rotor is to be found. Once knowing the temperature field change, the duplex grain defect long time existed in large forgings can be solved with a quantitative analysis instead of only the qualitative one. Precondition for small metal samples is brought to simulate microstructrure and grain size change of large rotor according to the numerical simulation result. also, con- sistent feature with real manufacture is showed from the physical experiment, so that the simula tion can be used to not only improve the products process but also prevent wasting unnecessary energy and shorten process periods. The rotor quality is controlled thoroughly with plenty of ex- periments data.