In this paper,  based on the fractal models of tonnage-average grade-cutoff grade models, the curves in selected orebody area of the typical gold deposits in the Sanjiang area, Yunnan Province, Southwest China, are calculated. The Reshuitang deposit mainly contains low-grade ores, and the other three have relatively high-grade. The characteristics of the tonnage-cutoff grade curves are analyzed, in which the mineralized dispersion index (MDI) is put forward. The greater MDI in Reshuitang deposit suggests the metal is more concentrated in this type of deposit.