In order to address the complex numerical calculations of the heat and mass transfer processes in the wet coating of electrode plates during convective drying, this study comprehensively considers the combined effects of hot air and the aluminum substrate on the thermal and mass transfer characteristics of the wet coating. Based on the multi-field coupling theory in porous media, a three-dimensional mathematical model of heat and mass transfer in the hot air-electrode plate wet coating is established using a meshless parallel method. Meanwhile, a difference calculation method for the heat and mass transfer process in the wet coating is proposed. Due to the high requirements for computational accuracy in mathematical model, a scale simulation method based on similarity theory is proposed to improve computational efficiency. The reliability of this method is validated through the comparison of temperature and humidity variations of wet coatings at different scaling ratios. The results show that the determination coefficient R² of humidity assessment of the wet coating at different scaling ratios is greater than 0.99. The simulation time for the original-scale model is 5 hours, while the simulation time for the scaled model with a scaling factor of 800 is 2.77 hours, representing a 44.6% reduction compared to the original model, thus effectively improving the numerical computation efficiency. Finally, the reliability of mathematical model is validated based on scale simulation method. The results show that the simulation temperature and humidity values from the hot air-electrode plate wet coating heat and mass transfer model have errors within ±15% of the experimental data, with only a few data points exhibiting slightly larger discrepancies, indicating that the model is reliable.