The multistage deep reduction process for preparing Ti6Al4V alloy powder has the notable advantages of cleanliness and high efficiency. This paper examined the leaching process of magnesiothermic self-propagating product, which was an intermediate product in the multistage deep reduction process. The influence of magnesiothermic self-propagating product particle size, HCl solution concentration and leaching solution temperature on the leaching behaviour of Al and V elements was investigated. The results demonstrated that the leaching rate of Al and V increased with the rise in leaching solution temperature, the increase in HCl solution concentration and the magnesiothermic self-propagating product particle size simultaneously. The leaching processe of Al and V were consistent with the chemical reaction control model. The magnesiothermic self-propagation product with a D₅₀ of 59.4 μm was ultimately selected as the raw material, leaching temperature of 40℃ and 1 mol/L HCl solution were employed as the leaching conditions. After 180 min of leaching, the loss rates of Al and V were 24.8% and 12.6%, respectively. The acid-leached product exhibited exhibited a porous structure with a specific surface area of 3.5633 m₂^/g.