Low cis polybutadiene (LCBR) is obtained by polymerization of butadiene initiated by alkali metal, alkyl lithium or other anionic polymerization initiators. The cis structure content of polybutadiene is usually about 40%. The trans structure content of LCBR is generally about 50%, and the 1,2 structure content is generally about 10%. The three structures are randomly distributed. LCBR has narrow molecular weight distribution, Poisson distribution, low degree of branching, excellent cold resistance and low temperature flexibility, good color, transparency, and even mass. LCBR is the preferred rubber for HIPS impact resistance modification.