Abstract: Using scallop as raw material and sodium stearate as modifier, the modified scallop powder was prepared by wet modification. Using single factor and response surface experiments to explore the effects of modification temperature, modifier dosage, and modification time on the modification effect of scallop shell powder. The scallop shell powder was characterized by Fourier infrared spectrometer, scanning electron microscope and X-ray diffractometer. The modified scallop shell powder and chitosan were made into a composite film, and the influence of the mass fraction of the modified scallop shell powder on the properties of the composite film was investigated. The experimental results showed that the best modification conditions of scallop shell powder were: Sodium stearate addition amount 2.53%, modification temperature 80.70 ℃, modification time 43.19 min. The activation of the fan shellshell powder produced under these conditions could reach up to 76.41%. Combined with characterization mapping analysis, sodium stearate was successfully incorporated onto the surface of shell powder, and the inter particle agglomeration of shell powder was weakened, and the prepared modified scallop shell powder showed good dispersion. Adding modified scallop shell powder could effectively improve the mechanical properties, light transmittance and water vapor barrier properties of the chitosan film. When the mass fraction of modified scallop powder was 1%, the performance of the composite film of modified scallop powder and chitosan was the best. At this time, the tensile strength of the film was 30.19 MPa, the elongation at break was 10.2%, the water vapor transmission rate was 35.1 g·h⁻¹·m⁻², and the light transmittance was 2.9 mm·%.