In order to explore the performance of bio asphalt / polyurethane composite modified asphalt, 28 kinds of bio as-phalt / polyurethane composite modified asphalt with different content were prepared. The performance was com-prehensively analyzed and evaluated by three index tests of asphalt, high and low temperature rheological tests and micro tests. The results show that the 15% bio asphalt and the 6% polyurethane is the best proportion; Compared with the control group, the high-temperature rutting resistance of the prepared bio asphalt / polyurethane compo-site modified asphalt is improved significantly, and the low-temperature performance is also improved. Chemical modification occurs inside the bio-asphalt-polyurethane composite modified asphalt. Which mixes evenly, forming a stable network filling structure. This study can provide reference for the research of similar modified asphalt materials.