With the increasing awareness of environmental protection and attention to resource reuse, the development of high-performance and degradable green biomass pavement materials attracts a lot of interest. Lignin and bio-oil effectively combined to play a synergistic role can improve various properties of asphalt and partially replace petroleum-based asphalt. Therefore, this paper aims to study the rheological and aging properties of bio-oil/lignin composite modified asphalt (OLMA) and determine the optimal dosage by Dynamic Shear Rheometer (DSR), Bending Beam Rheometer (BBR), and Fourier transforms infrared spectroscopy (FTIR) tests. From the DSR tests, it can be seen that OLMA can improve the high-temperature, fatigue, cracking, and relaxation performance of asphalt. BBR test obtained that OLMA can improve the asphalt's low-temperature performance and critical temperature. The method for evaluating the aging degree of composite modified asphalt was proposed. FTIR test results revealed that OLMA could reduce the increased rate of the aging index. The optimum dosage of 10% bio-oil and 20% lignin composite modified asphalt was determined. It proved that lignin and bio-oil are promising asphalt additives, modifiers, and replacements.