The invention relates to a fluvial facies sand body discontinuous boundary fine characterization seismic interpretation method. The method comprises the following steps: 1) according to fluvial facies sand body positive rhythmic deposition characteristics, in combination with demands on property extraction time window by subsequent property analysis, a sand body enveloping method is adopted to interpret construction of a sand body unit; 2) an ant tracking property and a curvature property are extracted on a target reservoir section; 3) the interpreted sand body is used for enveloping an extracted amplitude plane property, a curvature plane property and an ant tracking plane property with top bottom as time window; 4) a curvature plane property and an ant tracking plane property of a seismic profile are taken for comparison and analysis, and thus a sand body discontinuous boundary is judged; 5) vertical slice interpretation is carried out on the amplitude property, the discontinuous boundary caused by vertical overlapping of sand bodies are judged auxiliarily and a sand body deposition period is divided; 6) according to the discontinuous boundary plane judgment result acquired in the fourth step and the vertical sand body period dividing conclusion acquired in the fifth step, building of sedimentary facies recognition is assisted.