A case of binuclear manganese complex [Mn₂(L)₄(phen)₂(H₂O)₂] (1) was synthesized under solvothermal conditions with 2-naphthalic acid (HL) and 1,10-phenanthrenoline (phen) as ligands and manganese carbonate as the metal source. Complex 1 was characterized by single-crystal X-ray diffraction, elemental analysis, fourier transform infrared spectroscopy, powder X-ray diffraction, and thermogravimetric analysis. single-crystal X-ray diffraction shows that complex 1 belonged to the triclinic crystal system space group and the crystal cell parameters are a=0.769 89(5) nm, b=1.175 86(5) nm, c=1.668 30(9) nm, and α=107.074(5)°, β=96.167(5)°, γ=106.901(5)°. The asymmetric unit consists of a manganese ion, two 2-naphthoate anions, one 1,10-phenanthroline ligand and one water molecule, and Mn(II) atom is in a distorted octahedral configuration. The asymmetric units are bridged by carboxyl-oxygen atoms to form a dinuclear structure and then the binuclear structures are linked into a 2D supramolecular structure through π…π stacking interactions. The results of fluorescence spectroscopy show that complex 1 has good fluorescence performance and the maximum emission wavelength is 416 nm (λ_ex=302 nm). Thermogravimetric analysis shows that complex 1 remains stable to 117 ℃, and then begins to lose water of 3.18%, the structure after dehydration can stabilize at 223 ℃, after which the organic framework begins to collapse. Hirshfeld surface analysis is used to study the interaction between molecules.