The invention provides a thin mutual reservoir description method taking a reconstructed sand-to-ground ratio as a seismic description target. The method comprises steps of S1, explaining fine seismicstructures of top and bottom surfaces of a sand 
layer group; S2, generating a plurality of 
seismic attribute bodies by applying seismic means; S3, analyzing the correlation between the various seismic attributes and a sand-to-ground ratio and a net-to-gross ratio, determining whether the correlation has 
zoning or not, and selecting the seismic attributes with high correlation in zones for subsequent research; S4, respectively reconstructing the sand-to-ground ratio according to the zones in the S3, calculating the correlation between the reconstructed sand-to-ground ratio and the net-to-grossratio and the optimal seismic attributes, and giving a 
linear formula; S5, making an optimized 
seismic attribute planar graph, and converting the 
seismic attribute planar graph into a reconstructed sand-to-ground ratio or net-to-gross ratio planar distribution graph by utilizing the formula in the S4; and S6, deriving a sand-to-ground ratio and net-to-gross ratio 
planar graph by utilizing the reconstructed sand-to-ground ratio and net-to-gross ratio planar graph. The method is advantaged in that the reconstructed sand-to-ground ratio is utilized as the seismic description target, so the reconstructed sand-to-ground ratio and the seismic attributes have high similarity, the 
distribution rule of a thin mutual reservoir is effectively described, and the rule can effectively guide explorationand development practices.