The invention relates to a preparation method of high-performance liquid styrene butadiene rubber. The preparation method comprises the following steps: adding ethanol to a reaction flask; heating to reach 80 to 110 DEG C; adding terpene resin; agitating until terpene resin is dissolved completely; adding a dissolved thickening agent; uniformly agitating and mixing; sequentially adding water, styrene-butadiene latex, an emulsifying agent and a molecular weight regulator to a polymerizing pot; replacing with nitrogen; adding modified terpene resin; agitating and heating; adding an initiator while the temperature of the polymerizing pot reaches 30 to 60 DEG C; reacting for 5 to 8 hours under the polymerization temperature of 30 to 60 DEG C; adding a termination agent to obtain graft latex; adding the graft latex to a condensation kettle; adding water, an anti-aging agent and trialkyl amine chloride; agitating and heating; adding a coagulant under the coagulation temperature of 20 to 80 DEG C; agitating for 1 to 3 hours at 20 to 80 DEG C for ageing; and then washing, hydrating and drying to obtain the high-performance liquid styrene butadiene rubber. The prepared high-performance liquid styrene butadiene rubber has the characteristics that the bound styrene included ranges from 23.5 to 26.5, the number-average molecular weight reaches 3,000 to 5,000, the viscosity is 30 to 50 (25 DEG C) Pa.S, and the degree of functionality is close to 2.