Although the all-conjugated block copolymer has a great advantage of having a uniform phase separation, the synthetic process takes a long time, so, research has been less advanced. Thus, we tried to apply a continuous flow reactor to reduce the reaction time. Synthetic methods of all-conjugated block copolymer using the continuous flow reactor were investigated. Using P3HT-Br as a comonomer, P3HT-b-PTB7 and P3HTb-PNDIT were synthesized by Pd-catalyzed Stille polymerization. Compared to the conventional batch process, the reaction time was dramatically reduced from 36 hours to 35 minutes with chlorobenzene solvent. But, the reaction did not proceed well at initial temperature 120 ℃. After several temperature changes, 140 ℃ was found to be an appropriate temperature in chlorobenzene as solvent. Polydispersity (Ð) of the copolymers synthesized in flow reactor was generally lowered, however, the number average molecular weight (Mn) of the copolymers in flow reactor was also lower than the copolymers in batch. Due to the extent of copolymerization was very small, so we decided to change other conditions such as the type of catalyst and solvent. When the Pd catalyst becomes an active species, it must exist in a stable state to promote the reaction rate. However, chlorobenzene, the solvent used in the initial experiments, does not stabilize the active species of Pd catalyst, so the reaction rate is low. Therefore, in chlorobenzene, the type of catalyst was changed, and a direction for stabilizing the catalyst as a ligand was considered.