A tetranuclear Ln(Ⅲ)-based complex: [Dy₄(dbm)₄(L)₆(μ₃-OH)₂]·CH₃CN (1) (HL=5-[(4-methylbenzylidene)amino]quinolin-8-ol, Hdbm=dibenzoylmethane) was manufactured and its structure was characterized in detail. X-ray diffraction analysis shows that complex 1 belongs to the monoclinic crystal system and its space group is P2₁/n, which contains a rhombic Dy₄ core. Magnetic measurements of 1 suggest it possesses extraordinary single-molecule magnet (SMM) behavior. Its energy barrier U_eff/k_B was 116.7 K, and the pre-exponential coefficient τ₀=1.05×10^-8 s.