Abstract: Here was studied the influence of tetrahydrofuran on the 1,2-content of polybutadiene in anionic polymerizaton for preparing polybutadiene and block copolymer SBS by using n-butyl lithium as initiator in solution of cyclohexane.The experiments showed that at given temperatures the 1,2-content of polybutadiene is a exponential function of the concentration of THF,so the 1,2-content of polybutadiene can be controlled by changing the concentration of THFat given temperature of polymerization.