To make up for the deficiency of Trinidad Lake asphalt（TLA） in some aspects, it was considered to add styrene-butadiene-styrene（SBS） modifier. Firstly, the modification mechanism of TLA was analyzed from the microscopic and chemical composition. Then TLA and TLA/SBS composite modified asphalt were tested respectively, and the dynamic stability, stability, water stability, low temperature cracking resistance, fatigue resistance, dynamic modulus and other indexes of TLA/SBS asphalt mixture with different TLA content were tested. The results show that the softening point, ductility and viscosity of base asphalt are significantly improved by the composite modification, generally over 45%. After the composite modification, various indexes of asphalt mixture have been significantly improved, especially the high and low temperature stability, anti-fatigue performance, dynamic modulus increase range of 13%~86%, with excellent pavement performance. Finally, the optimal SBS content in asphalt mixture should be 5%, and TLA content is 20%.