Abstract: ⁹⁰Y/¹⁷⁷Lu labeled DOTA-Bz-RGD tetramer and DOTA-RGD tetramer were prepared, and the effect of Bz-DOTA and DOTA on labeling conditions and in vitro stability of radiolabeled compounds was compared. The labeling conditions, including reaction pH, reaction temperature and reaction time, were investigated. ITLC and HPLC show that the labeling yields of four radiolabeled compounds are more than 95% under optimal conditions (pH=6.0, reacting at 100 ℃ for 15-20 min); the four radiolabeled compounds show pretty good stability in saline and fetal bovine serum. Although introducing of Bz has no effect on labeling conditions and in vitrostability of radiolabeled compounds, it brings a little change on molecule polarity. HPLC analysisand lg P values reveal that introducing of Bz increases the lipophilicity of radiolabeled compounds.