The invention discloses an SOM classification technology-based estuary river basin water environment quality evaluation method, which comprises the following steps: collecting estuary river basin water quality data and spatial geography data, and compiling into a data table; carrying out pretreatment on a geographic map layer to form a water quality analysis base map, and introducing into the data table through a data processing module, and generating a point data map layer; calculating the water quality data by an SOM classifying function, exporting the classifying result as classified data in a table form; generating a classified data map layer according to the longitude and latitude of the classifying data; carrying out inverse distance weighted interpolation analysis on the classified data map layer to generate an interpolation map layer; and adjusting and modifying the interpolation map layer and the base map to obtain a water quality distribution map. According to the SOM classification technology-based estuary river basin water environment quality evaluation method, organic unification of water quality data evaluation and visualization is achieved; the data are directly and rapidly analyzed; result visualization is achieved; the analysis result is relatively close to the actual condition; and the analysis accuracy is greatly improved.