The invention provides a control method for 1, 2-level structure contents in styrene/butadiene block copolymer PB chain, which are used for hydrogenation. The structure regulator system is composed of two polar modifiers, and used to regulate the microstructure of polybutadiene. The regulation system has high efficiency and low consumption, and is not sensitive to temperature. The stability control of Bv content can be realized in the temperature-changing polymerization process.