Abstract: A mathematical model was built up to realize a quick reserve evaluation of polymetallic deposits based on a multidimensional probability distribution function in view of that there exists a certain correlation between valuable components in the polymetallie deposits. The model was verified by studying a gold-copper deposit ease. In the case, it was proved that the probability density of both Au and Cu grades obeys a logarithmic normal distribution, based on which the correlation between them was verified. Then a function of the muhidimensional probability distribution of grades in the gold-copper deposit was established after the probability density distribution was expanded from one-dimension to muhi-dimension. The corresponding reserves for different cut-off grades were calculated with the help of the function. The model was proved reliable for the calculation error was less than 10%, which is an accepted accuracy for reserve evaluations.