To evaluate the low-temperature performance of double screw activated rubber powder composite SBS modified asphalt and its mixture， the low-temperature performance indicators of SBS modified asphalt， non-activated rubber powder composite SBS modified asphalt， and twin-screw activated rubber powder composite SBS modified asphalt were tested by force ductility， semi-circular bending， and overlay test. The entropy weight method was used to optimize the force ductility indicators. The mechanism of performance changes of the three types of asphalt was analyzed through fluorescence microscopy and four component testing. The results indicate that the maximum yield point of the force ductility index can effectively characterizes the low-temperature performance of twin-screw activated rubber powder composite SBS modified asphalt. During the twin-screw activation process， crosslinks are opened and a stable crosslink network structure is formed with SBS， significantly enhancing the high-temperature performance and resistance to water damage of the modified asphalt mixtures.