The work aims to embed polyvalerolactone (PVL) soft chain into the structure of TMT in order to improve the viscosity-temperature performance of TMT base oil in view of that the application of trimellitate (TMT) in the lubricating oil industry is seriously restricted due to its low viscosity-temperature performance. δ-valerolactone (DVL) ring-opening polymerization was initiated at 60 ℃ to form four-arm star polyvalerolactone (4-PVL) with tetrabutyl titanate (TBT) as an initiator. Then, hydroxyl terminated linear polyvalerolactone (L-PVL) was obtained by hydrolyzed under acidic condition. The reaction between L-PVL and trimellitic anhydride (TMA) produced an embedded polymer intermediate, which was esterified with isobutanol to obtain PVL modified TMT lube base oil. Modified base oil was analyzed by 1H-NMR, FTIR, TG and Mass spectrum. The viscosity, viscosity index and pour point of modified base oil were tested by ASTM standard and the wear scar morphology was analyzed by SEM. The modified TMT base oil was superior to unmodified one in performances of viscosity temperature, thermal stability and anti-wear. The viscosity index of modified TMT base oil increased with the increase of embedded chain length, and the viscosity index of the 4-PVL modified TMT increased from 8 to 103. At the same time, the thermal stability of the base oil was enhanced by the embedded polymer, and the initial oxidation decomposition temperature increased from 203 ℃ to 250 ℃. In addition, the anti-wear performance of the modified base oil was also improved, and the average wear spot diameter reduced from 1330 μm to 1028 μm. The quality and performance of TMT base oil are improved significantly by modifying TMT base oil by chemical means with PVL as embedded chain. Through optimization of performance and cost, it is determined that modified TMT base oil shows optimal comprehensive performance with PVL (n=4).