This paper studied the performance of bio-asphalt and rock asphalt composite modified asphalt binder. To investigate the change of the properties of asphalt subjected to the composite modification of bio-asphalt and rock asphalt, tests on the penetration, softening point, ductility, viscosity and RTFO short-term aging of the bio-asphalt and rock asphalt composite modified asphalt binder with different content in the range of 60% were carried out. The test results and analysis indicate that when the 25 ℃ penetration of bio-asphalt and rock asphalt composite modified asphalt is consistent with the base asphalt binder, the ratio of rock asphalt to bio-asphalt are proportional to the content of composite modifier; The penetration index PI value of composite modified asphalt binder increases and the temperature sensitivity improves. The high temperature performance of composite modified asphalt decreases slightly first and then increases, and reaches its original level when the content of composite modifier is about 15%; The retained penetration of composite modified asphalt after RTFO decreases slightly first and then increases always, and finally reaches its original level when the content of composite modifier is about 20%, and the change of softening point increases obviously; However, the ductility of asphalt decreases significantly with the addition of the composite modifier. However, the bending test of asphalt mixture demonstrates that the addition of composite modifier does not decrease the low temperature performance of asphalt and improves it to some extent. In a whole, within the content from 20% to 30%, replacing some petroleum asphalt with compound modifier improves the performance of asphalt. Furthermore, the upper or lower content limit can be broadened appropriately when different performance requirements are to be met.