A novel 1D Ladder-like coordination polymer [Na3Er(2,6-PDA)3]·11.5H2O (2,6-H2PDA is pyridine-2,6-dicarboxylic acid) has been synthesized and the crystal structure was determined by X-ray diffraction. The crystal structure of the complex belongs to Monoclinic system with space group P21/c, a=0.969 7(3) nm, b=1.914 6(6) nm, c=1.803 1(6) nm, β=91.524(5)°, V=3.346 6(18) mm3, Z=4, Dc=1.863 g·cm-3, μ=2.645 mm-1. The coordination geometry configuration of Er3+ center is tricapped trigonal prism. The structures of the title compound exhibit a novel 1D Ladder-like chain.