Recently, layered double hydroxides (LDH) have been proven to be promising adsorbents in the field of wastewater treatment mainly due to their unique characteristics. In this study, a series of Mg_xAl-LDH (x is the molar ratio of Mg/Al) were synthesized via a supersaturated co-precipitation method and used for the removal of low concentration nitrate (NO₃⁻). Based on the results, Mg₅Al-LDH showed a significantly enhanced adsorption capacity of 9.76 mg g⁻¹, and the removal efficiency of NO₃⁻ (C₀ = 1 mg L⁻¹) reached about 80% after 6 h at 25 °C and neutral pH. As proved by various characterization studies, changes in the molar ratio of Mg/Al would influence the surface active groups and layer distance of the synthesized LDH, thereby affecting the adsorption of NO₃⁻. In addition, the synthesized LDH presented a mesoporous structure, which can reduce the obstruction for adsorbing NO₃⁻. Studies on the reaction kinetics indicated that the NO₃⁻ adsorption behavior of Mg₅Al-LDH can be well fitted by the pseudo-second-order kinetic and Langmuir models, demonstrating that the resultant adsorption is a spontaneous, exothermic and entropy decreasing process with physical and chemical effects simultaneously. By further clarifying the mechanisms of NO₃⁻ removal, the synthesized Mg₅Al-LDH could be thought of as an efficient, environmentally friendly, and low-cost adsorbent to remove NO₃⁻ from the aquatic environment.