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The natural nacre has a regular ordered layered structure of calcium carbonate tablets and ion crosslinking proteins stacked alternately, showing outstanding mechanical properties. Inspired by nacre, we fabricated different divalent metal cation-crosslinked montmorillonite-alginate hybrid films (MMT-ALG-X²⁺; X²⁺ = Cu²⁺, Cd²⁺, Ba²⁺, Ca²⁺, Ni²⁺, Co²⁺ or Mn²⁺). The effect of ionic crosslinking strength and hydrogen bond interaction on the mechanical properties of the nacre-mimetics was studied. With the cations affinities with ALG being increased (Mn²⁺ < Co²⁺ = Ni²⁺ < Ca²⁺ < Ba²⁺ < Cd²⁺ < Cu²⁺), the tensile strength of nacre-mimetics showed two opposite influence trends: Weak ionic crosslinking (Mn²⁺, Co²⁺, Ni²⁺ and Ca²⁺) can synergize with hydrogen bonds to greatly increase the tensile properties of the sample; Strong ionic crosslinking (Ba²⁺, Cd²⁺, Cu²⁺) and hydrogen bonding form a competitive relationship, resulting in a rapid decrease in mechanical properties. Mn²⁺ crosslinking generates optimal strength of 288.0 ± 15.2 MPa with an ultimate strain of 5.35 ± 0.6%, obviously superior to natural nacre (135 MPa and 2%). These excellent mechanical properties arise from the optimum synergy of ion crosslinking and interfacial hydrogen bonds between crosslinked ALG and MMT nanosheets. In addition, these metal ion-crosslinked composite films show different colors, high visible transparency, and excellent UV shielding properties.