MOFs-based adsorbents with electronic complexity and steric diversity become promising platform for heavy metal wastewater treatment. However, experimentally confirming the effect of ligand effects on Sb(V) adsorption with MOFs materials has remained a fundamental challenge. Herein, ligand-engineering strategy are implemented to synthesize five absorbents (La-para-PTAs, La-ortho-PTAs, La-meta-PTAs, La-MCs and La-MGs) and propose that the adsorption performance is correlate directly with of the utilization of accessible adsorption site. Within the meta-substituted –COOH coordination and imidazole ring, La-MGs achieve almost 92% site utilization promoting the state-of-the-art value of 896.5 mg/g for Sb(V) removal. Rational change of –COOH substituent locations from La-para-PTAs to La-meta-PTAs results in larger BET surface area and bigger pore volume, improving the accessibility of adsorption sites. Based on XPS results and DFT calculations, the strong interaction between La-MGs and Sb(V), which significantly promotes the charge transfer of removal process and increases the content of electron state around the Fermi energy in La 5d and 6 s orbits thus lower the adsorption energy of La-MGs for Sb(V). This work provides insights into the rational design of the definitive structure of MOFs-based adsorbents with tunable adsorption performance for efficient energy conversion toxic metal oxyanion remediation from the viewpoint of adsorption sites utilization.