One micro-powder rubber (styrene butadiene rubber-SBR) at three concentration levels are used for manufacturing polymer modified asphalt with a mixing technique. The effects of concentration of modifiers and mixing temperature on the mechanical properties of the compounds are investigated. Based on a limited study, test results indicate that micro-powder rubbers have positive effect on the performance of asphalt in low temperature. Soft point, penetration and ductility show that the ideal percentage of rubber additive (7 wt. %) and preparing temperature (210°C) are brought forward. The fluorescence microscopy test indicates that rubbers are homogeneous dispersed in asphalt and have a little dissolving at the surface of the ultra-fine rubbers. The difference between soft point values in the high temperature storage stability test is only 0.2~0.5°C, which proves that modified asphalts have good storage stability. Complex modulus master curves are drawn to analyze and compare the rheological properties of various modified asphalts. Results indicate that modified asphalt binders have more excellent properties at both high and low temperatures, compared with original asphalt.