The invention discloses a method for synthesizing a wide-particle-size-distribution nickel-cobalt-aluminum positive electrode material precursor through continuous coprecipitation. Through coprecipitation in a reactor, spherical nickel cobalt aluminum hydroxide powder with wide particle size distribution is synthesized. In the synthesis process, two stages of starting kettle reaction for constructing particle size gradient and maintaining particle size stability are carried out separately, process parameter control is carried out according to different pH value process conditions; overflow liquid is subjected to synthesis treatment for eliminating micro powder, so that the nickel cobalt aluminum hydroxide powder with wide particle size distribution is obtain; and after solid-liquid separation, residues in the powder are removed in a reinforced washing mode, dispersity of the powder is guaranteed, and after full drying, a nickel-cobalt-aluminum positive electrode material precursor withan adjustable average particle size D50 in a range of 10-15 [mu]m and a tap density of 2.0 g/cm<3> or above is prepared. The preparation method is simple in technological process and suitable for industrial large-scale production of the nickel-cobalt-aluminum positive electrode material precursor.