Abstract: An anode active material for a battery and a preparation method thereof, a battery anode, and a secondary battery. The anode active material for a battery includes anode active substance particles, where the anode active substance particles include silicon oxide compounds and lithium; in the X-ray diffraction using Cu-K? radiation, the anode active substance particles have a first diffraction peak in a range of 2?=18.78°±0.2° and a second diffraction peak in a range of 2?=47.4°±0.3°; and a full width at half maximum of the first diffraction peak is set as A, A is greater than 0.34°, a full width at half maximum of the second diffraction peak is set as B, and B/A?1.3. The anode active material for a battery has superior electrochemical properties, including high energy density and excellent kinetic performance when employed in batteries.