The invention discloses a method for finely classifying acidized water injection wells. The method comprises the following steps: basic data of the water injection wells are collected; injected waterused for the water injection wells is subjected to water quality analysis, and the content of suspended solids and the diameter mid-value of suspended particles in the injected water are obtained; therelative diameter of the suspended particles is calculated; cores of reservoirs of the water injection wells are collected as rock samples, and the permeability of the reservoir cores before injectedwater pollution and the permeability of the reservoir cores after injected water pollution are measured through a core displacement experimental device; the degree of pollution of the injected waterto the reservoir cores is calculated, and the radius of a mud pollution zone is calculated according to a formation test pressure recovery curve; the water injection wells are classified; and finallyaccording to classification, the classified water injection wells are described and evaluated. According to the method, the acidized water injection wells of a fault-block oil and gas field can be classified into four categories, the reservoir damage mechanism of the various water injection wells is analyzed, and on the basis, more targeted acidification modification ideas are provided for each category of water injection wells.