Through scanning electron microscope (SEM), spectral analysis, and component analysis tests, the interaction theory between asphalt and rubber was discussed. It is concluded that rubber powder become soft and bond together with each other after being mixed with asphalt. The asphalt changes from a smooth homogeneous matter to a continuous mixing system which is composed of rubber powder and asphalt. The interaction is mainly physical diffusion, but there are some chemical reactions in the process, especially at long reaction time. Through scanning electron microscope (SEM), spectral analysis, and component analysis tests, the interaction theory between asphalt and rubber was discussed. It is said that that rubber powder become soft and bond together with each other after being mixed with asphalt. a smooth homogeneous matter to a continuous mixing system which is composed of rubber powder and asphalt. The interaction is mainly physical diffusion, but there are some chemical reactions in the process, especially at long reaction time.