The effect of fiber on the asphalt mixtures has been concerned at all times. Bearing this problem in mind, four kinds of polyester fiber, one kind of methyl cellulose, one kind of mineral fiber, AC-16 and SMA-16 asphalt mixtures, AH-70 and the SBS (I-D) modified asphalt were chosen and used in the present study. Practical performances such as Marshall Test indexes, low-temperature split strength, residual stability, freezing and thawing splitting strength ratio and dynamic stability of the mixtures made of the above mentioned materials were studied. Though there is optimal asphalt content contained in the mixture, the improving effect of fiber on the asphalt mixtures (AC-16 and SMA-16) performance is not apparent. Therefore from a general view of economy and technology, it seems unnecessary to put fiber into AC asphalt mixtures with high-quality modified asphalts. However, the effect of fiber as a stabilizing agent is bigger than that of as the agent strengthening the wheel tracking resistance capacity in the SMA mixtures.