A method of suppressing self oscillation of a partial end-pumped slab amplifier via discrete amplification paths is disclosed. According to the method, devices that are employed comprise a first reflecting mirror, a second reflecting mirror, an Innoslab amplification crystal, a red copper crystal frame, a semiconductor diode array, a dichroic mirror, a third reflecting mirror and a fourth reflecting mirror. According to the method, seed light to be amplified is subjected to pitching and deflection adjustment via the first to the fourth (or more) reflecting mirrors and the dichroic mirror, and then the seed light is amplified via the Innoslab amplification crystal for five times (or more). According to the method, pitching characteristics, independent of each other, of a plurality of the reflecting mirrors in the amplifier are used enable the amplification paths to be distributed on several discrete planes; that two side cavity mirrors of the amplification crystal are not parallel in a vertical direction can be ensured, and therefore starting of self oscillation of can be suppressed; incident angles of all reflected light are respectively controlled, the reflected light is enabled to well pass through a pumping area of the amplification crystal and mode matching is maintained; final energy drawing efficiency is improved.