Adding soluble polymers into the protein solution is one of the traditional techniques to prevent protein aggregation.The mechanism of this process，however，is not well understood.Dynamic Monte Carlo simulation was used to investigate the molecular assembly formed between 2D model proteins and 2D model polymers with different hydrophobicity values，molecular weight and concentration.It was shown that polymer with a moderate hydrophobicity value could prevent protein aggregation and thus stabilize the native structure via forming protein-polymer complex.It was also shown that the increase of molecular weight and concentration of polymer could prevent protein aggregation.The snapshots of protein-polymer complex and the distribution of protein conformations showed that the polymers with a suitable hydrophobicity value，molecular weight and concentration，could assemble around the surface of model protein via weakly hydrophobic interaction to disperse protein，thus avoiding protein-protein interaction，which leads to the aggregation.The above dynamic Monte Carlo simulation agreed well with experimental observations reported in literature.The molecular insight of polymer-protein interactions，as established by the present simulation，can be used to guide the design and application of polymers as protein stabilizer in bioprocessing engineering.