Abstract: Protein is an important component of natural latex (NR). However, it is easy to migrate onto the surface during the process of film formation, resulting in high protein spillover, which leads to allergies and mildew easily. Traditional solutions such as chlorination and radiation are very complex and tend to cause serious environmental pollution issues. Dialdehyde sodium alginate (DASA) has a strong covalent cross-linking effect on proteins and there are few reports on the reduction of NR protein spillover. In this paper, DASA was prepared by oxidation of sodium alginate with sodium periodate. The results showed that the oxidation degree of DASA increased with the concentration of sodium periodate, but the molecular weight decreased. The protein spillage of NR/DASA composite film prepared by physical blending decreased from 1 420 μg/g to 42 μg/g, indicating that the covalent cross-linking reaction between the aldehyde group in DASA and the protein decreased the mobility of proteins, hence greatly reduced the protein spillover of NR/DASA film. Meanwhile mildew and contact allergy effect can be alleviated. The uniform distribution of the protein in NR film can also increase the solubility of the vulcanization accelerator, which makes the vulcanization reaction easier. Furthermore, the protein can also consume the peroxide radicals generated in the NR film during storage, thus lowering its aging rate. The tests of mechanical properties show that the tensile strength of NR/DASA composite film increases by 28.9% after vulcanization, and only decreases by 2.7 MPa after accelerating the aging treatment. Atomic force microscopy (AFM) and thermogravimetric (TG) analysis show that the surface smoothness and thermal degradation resistance of the NR/DASA films are also significantly improved. In addition, the solvent resistance of NR/DASA films in cyclohexane and petroleum ether is also greatly improved.