Abstract: In this paper the study of propylene dimerization catalyzed by β-diketonat∂ complexes of light rare-earth metals is presented catalyst Pr (acac)₃·H₂O/Et₃Al₂ Cl₃/PPh₃ showed higher activity of 1200-1300 molC₃^-/molPr.h and conversion rate of 50-60% in dimerization under the reaction conditions Pr(acac)₃·H₂O, 0.05-0.3mmol; Al/Pr ratio, 30-50;P/Pr ratio, 3-6 and temperature 60-80℃. For systems RE(acac)₃ /Et₃Al₂Cl₃/PPh₃ and Pr(β-diketonates)₃·χH₂O/Et₃ Al₂Cl₃/PPh₃,the catalyst activity decreased in the following order: for rare earths: Ce～Pr>La>Nd>Sm for ligands: hfacac>acac>DBM. All catalyst systems studied gave a close weight percentage of products: methylpentenes of 64-66% and linear hexenes of 24.1-26.4 with dimer selectivity of 77-93.3%.