Traditional acoustic metamaterials face issues including narrow noise reduction frequency range, highcost, and difficulty in implementation. To address these problems, a Helmholtz resonant cavity acoustic metamaterialstructure with a flexible thin film is proposed. Starting from the phenomenon of local resonance couplingeffects, mathematical models of the Helmholtz resonant cavity and the flexible thin film are derived. These modelsare simulated and analyzed using COMSOL Multiphysics software. The results show that the structure producestwo local resonance peaks. To achieve control over the noise reduction frequency band of the acoustic metamaterial,liquid is injected into the thin film. Experimental results show that when the injection volume increases from 0 to35 mL, the resonance frequency of the thin film shifts from 612 Hz to 446 Hz, resulting in a displacement of166 Hz. The designed local resonance acoustic metamaterial effectively controls low-frequency noise within the specifiedfrequency band, providing a novel approach for the design of acoustic metamaterials.