Abstract: The study investigated the temperature, strain, and plastic flow of high-strength aluminum alloy 2219-T8 during the initial feed stage of the additive friction stir deposition process. The influence of spindle rotational speed and material feed rate on material flow was thoroughly discussed. A three-dimensional finite element thermodynamic model was established using Arrhenius' material law. The experimental results indicate that there is a variation in deposition time within the same region under different process parameters. The optimal process parameter settings for achieving the fastest deposition speed and highest material enhancement efficiency are a spindle speed of 350 r/min and a feed rate of 0.2 mm/s. Increasing the spindle speed results in a higher heating rate of the feed rod, which in turn increases the highest temperature at which the material undergoes plastic deformation and the strain rate. On the other hand, increasing the material feed rate decreases the material mobility, which increases the time required to fill the gap between the stirring shaft and the substrate.