Microstructure development of grain oriented silicon steel with main inhibitor Cu2S was studied in thin slab casting and rolling total process, conventional and optimized technological process were compared. The results showed that through optimized technological the microstructure form cast iron to finished product of grain oriented silicon steel produced by TSCR changed greatly, but the subgrain size of finished product is almost same to that of conventional technological; after technological be optimized, primary recryatal grains were finer and more uniform, the secondly recrystallization advances perfectly, the magnetic performance was improved; techniques to produce grain oriented silicon steel with main inhibitor Cu2S by TSCR is viable.