Polyethylene glycol 400 was grafted onto carbon black (CB) surface by means of in- situ liquid method,and the properties of natural rubber respectively reinforced by carbon black and grafted carbon black were investiga-ted.The results show that (1) at the same filler dosage,both the scorch time and the curing time of grafted carbonblack- filled rubber shorten,and the physical and mechanical properties obviously improve; and (2) as comparedwith the natural rubber reinforced by carbon black,the rubber reinforced by grafted carbon black with a filler dosageof 50 parts is of bound rubber content increment of 16.5%,tensile strength increment and tear strength incrementof 6.1MPa and 19.5kN/m,respectively,abrasion loss decreasing from 0.53g to 0.37g,and tanδ value decrementat 0,60 and 80℃ of 16.67%,45.23% and 45.45%,respectively.Moreover,the results of dynamic mechanicalanalysis and SEM test show that the performance improvement of rubber compound mainly owes to better dispersionof grafted carbon black in natural rubber matrix and greater interaction between grafted carbon black and naturalrubber matrix.