Abstract: The mining investment that can be delayed is equal to a real option.Based on the improved decision-making model of best mining investment timing，the critical price and value of zinc mine investment at abroad were analyzed.The results showed that the critical price of the zinc mining investment P* is $2 069.69 and the critical value V(P*) is $348.60.It is feasible to invest the zinc mining project in 2010.The critical price of the zinc mining is most sensitive to production cost C.If the production cost C decreases by 1%，the critical price will be reduced by 0.772 1%.The critical value is most sensitive to convenience yield δ.If the convenience yield decreases by 1%，the critical value will be increased by 1.329 7%.

Key words: Real option, Mining investment timing, Critical price