In this paper,thetudy low granulated recycled LDPE materials are used to prepare modified asphalt and to conduct the combination material performance testing for SMA-13 mixture.SMA-13 is graded to optimize and determine the best aggregate ratio.According to the optimal Whetstone ratio,the molding mixture specimen is made to study low temperature performance and water stability performance.The study shows that :70# asphalt is compared with 6% of LDPE modified asphalt so that the SMA-13 DS increased by 4 times;LDPE modified asphalt -10℃ low temperature limit bending strain is 3900 με,freeze-thaw cleavage strength ratio and re