Three isostructural lanthanide complexes, namely [Ln(L)₃·CH₃OH] (Ln = Tb(1), Dy(2), Ho(3), HL = N-(pyridin-2-ylcarbamothioyl)benzamide), were successfully synthesized and characterized by IR, UV, elemental analysis, single-crystal X-ray diffraction and DNA-biding analysis. X-ray single-crystal diffractions show that the family of lanthanide complexes crystallizes in monoclinic C2/c space group. Each lanthanide atom is coordinated with three carbonyl-O atoms, three pyridyl-N atoms and three imine-N atoms from three distinct L^–1 ligands, forming a distorted tricapped trigonal prism. The binding properties of complexes with ct-DNA were studied by simulating the physiological environment of human body. The results suggest that compounds could bind with ct-DNA through interaction under a spontaneous process.