One new Mn(II) coordination polymer, [Mn(Htia)₂(H₂O)₂]_n·2nH₂O (1, H₂tia = 4-(1,2,4-triazol- 1-yl)isophthalic acid) has been synthesized in mixed solvents under solvothermal conditions. Further characterizations including single-crystal XRD, elemental analysis, IR spectroscopy, thermogravimetric analysis and powder XRD were performed to verify the structure.  Complex 1 displays a one-dimensional (1D) chain and is similar to a reported Mn(II) complex 2 {[Mn(Htta)₂(H₂O)₂]·2H₂O}_n. It crystallizes in triclinic P space group, with a = 7.5557 (3), b = 7.5974 (3), c = 11.8448 (4) Å, α = 90.088(1)°, β = 95.863(1)°, γ = 113.668(1)°, V = 618.81(4) ų, Z = 1, M_r = 591.36 g/mol, D_c = 1.587 mg/m³, μ = 0.609 mm^-1, F(000) = 303, GOOF = 1.062, the final R = 0.0359 and wR = 0.0818 for 4272 observed reflections with I > 2σ(I). Based on two similar structures, Hirshfeld surface analysis confirmed both structures are mainly stabilized by O···H/H···O and C···H/H···C hydrogen bonds. Further, weak ferromagnetic behaviors between adjacent Mn(II) ions in 1D chain are obtained.