A method for preparing reduced titanium powder by multistage deep reduction, characterized by comprising the following steps: Step 1: self-propagating reaction placing titanium dioxide powder in a drying oven, performing drying to obtain dried titanium dioxide powder, uniformly mixing the dried titanium dioxide powder with magnesium powder to obtain a mixture, adding the mixture in a self-propagating reaction furnace, after reacted materials are cooled, obtaining an intermediate product of which low-valence titanium oxides Ti x O are dispersed in an MgO matrix, wherein TiO 2: Mg = 1: (0.8-1.2) (molar ratio), and the intermediate product of which the low-valence titanium oxides Ti x O dispersed in the MgO matrix is a mixture of non-stoichiometric-ratio low-valence titanium oxides, with x being in the range of 0.6-1; Step 2: first-time leaching placing the intermediate product of which the low-valence titanium oxides Ti x O are dispersed in the MgO matrix in a sealed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution to obtain filtrate and a leached product, removing the filtrate, washing the leached product, and performing vacuum drying to obtain a low-valence titanium oxide TixO precursor, wherein the molar concentration of the hydrochloric acid is 1-6 mol/L; Step 3: second-time deep reduction uniformly mixing the low-valence titanium oxide Ti x O precursor with calcium powder, and performing pressing at 2-20 MPa to obtain block-shaped semi-finished products, placing the block-shaped semi-finished products in a vacuum reduction furnace, performing heating to raise the temperature to 700-1200 DEG C, performing second-time deep reduction for 1-6 h, after second-time deep reduction, obtaining block-shaped semi-finished products, cooling the block-shaped semi-finished products along with the furnace to obtain a deep reduction product, wherein Ti x O: Ca = 1: (1.5-3) (molar ratio) in the low-valence titanium oxide Ti x O precursor; Step 4: second-time leaching placing the deep reduction product in the sealed reaction kettle, leaching the deep reduction product with hydrochloric acid as the leaching solution to obtain filtrate and filtered residues, removing the leaching solution, washing the filtered residues, and performing vacuum drying so as to obtain reduced titanium powder, wherein the molar concentration of hydrochloric acid is 1-6 mol/L, wherein reduced titanium powder comprises the following components in percentage by mass of 98-99.5% of Ti, 0.1-2% of O, and the balance being unavoidable impurities, with size of 8-40 μm. Step 1: self-propagating reaction placing titanium dioxide powder in a drying oven, performing drying to obtain dried titanium dioxide powder, uniformly mixing the dried titanium dioxide powder with magnesium powder to obtain a mixture, adding the mixture in a self-propagating reaction furnace, after reacted materials are cooled, obtaining an intermediate product of which low-valence titanium oxides Ti x O are dispersed in an MgO matrix, wherein TiO 2: Mg = 1: (0.8-1.2) (molar ratio), and the intermediate product of which the low-valence titanium oxides Ti x O dispersed in the MgO matrix is a mixture of non-stoichiometric-ratio low-valence titanium oxides, with x being in the range of 0.6-1; Step 2: first-time leaching placing the intermediate product of which the low-valence titanium oxides Ti x O are dispersed in the MgO matrix in a sealed reaction kettle, leaching the intermediate product with hydrochloric acid as a leaching solution to obtain filtrate and a leached product, removing the filtrate, washing the leached product, and performing vacuum drying to obtain a low-valence titanium oxide TixO precursor, wherein the molar concentration of the hydrochloric acid is 1-6 mol/L; Step 3: second-time deep reduction uniformly mixing the low-valence titanium oxide Ti x O precursor with calcium powder, and performing pressing at 2-20 MPa to obtain block-shaped semi-finished products, placing the block-shaped semi-finished products in a vacuum reduction furnace, performing heating to raise the temperature to 700-1200 DEG C, performing second-time deep reduction for 1-6 h, after second-time deep reduction, obtaining block-shaped semi-finished products, cooling the block-shaped semi-finished products along with the furnace to obtain a deep reduction product, wherein Ti x O: Ca = 1: (1.5-3) (molar ratio) in the low-valence titanium oxide Ti x O precursor; Step 4: second-time leaching placing the deep reduction product in the sealed reaction kettle, leaching the deep reduction product with hydrochloric acid as the leaching solution to obtain filtrate and filtered residues, removing the leaching solution, washing the filtered residues, and performing vacuum drying so as to obtain reduced titanium powder, wherein the molar concentration of hydrochloric acid is 1-6 mol/L, wherein reduced titanium powder comprises the following components in percentage by mass of 98-99.5% of Ti, 0.1-2% of O, and the balance being unavoidable impurities, with size of 8-40 μm.