A new polyoxometalate dimer based on lacunary Wells-Dawson anion and lanthanide cation, Na14[{Nd(H2O)3 (α2-P2W17O61)}2]·17H2O, was isolated as a sodium salt under ambient conditions and characterized by IR, TG, and X-ray single crystal structure analysis and electrochemistry. It belonged to the triclinic, space group Pī with a=1.26738 (15) nm, b=1.41464 (17) nm, c=2.3254 (4) nm, α=103.142 (2)°, β = 95.122 (2)°, γ=113.9690 (10)°, V=3.6317 (8)nm3, Z=2, Dc=4.274 mg/m3, and μ=27.695 mm-1. The Nd3+ ion was substituted for a [W=O]4+ unit in the "cap" site of the tungsten-oxygen framework of the parent Wells-Dawson ion. The cyclic voltammograms of the title compound exhibited nearly chemically reversible one-step one-electron transfer process and two-step irreversible reduction processes. Thermogravimetric showed a one-step slow weight loss stage in the range of 25-850 ℃.