On the basis of DSR test,the influence of diatomite quality and difference in base asphalt on the rheological property of modified asphalt was analyzed by choosing diatomite from different phase of mineral refining and base asphalt with different oil source and grade to modify asphalt separately. The results indicate that purified diatomite obtained after mineral refining can improve the anti-deformation property of asphalt effectively,but the modification effect of original diatomite and tailing diatomite is no good;the anti-deformation property of modified asphalt is also affected by base asphalt with different oil source,and it will make a different modification effect;at the same time,the higher grade of base asphalt,the lower anti-deformation property of asphalt after modification.