Abstract: ^177 Lu DOTA Bz RGD dimer and  ¹⁷⁷ Lu DOTA Bz PEG4 RGD dimer were prepared, and the effect of PEG4 on labeling conditions and in vitro stability as well as pharmacokinetic properties and biodistribution in normal mice for the radiolebeled compounds was compared. The results of TLC and HPLC show that the labeling yield of two radiolabeled compounds was more than 95% under optimal conditions (pH 4.0 and pH 6.0, respectively, reacting at 100 ℃ for 15 20 min). The two radiolabeled compounds show pretty good stability in saline. HPLC analyses and lg P ow values revealed that introducing of PEG4 increased the lipophilic character of radiolabeled compounds, but had no significant changes on pharmacokinetic properties and biodistribution in normal mice.