Abstarct: Copper is one of the most useful mextals in today industry. The investment cost in mining activities such as exploration and processing is very high. Therefore any misunderstanding of the factors affecting the project, the investment maybe associates with high risk. Fluctuating economic parameters such as price and costs, are the most important factors affecting mining projects that must be analyzed. The purpose of this study was to evaluate uncertainty of economical parameters in the Takht Gonbad Sirjan Copper mine. To achieve this aim, at first ore reserve estimation process is performed using Kriging method. The estimated model yielded the reserve tonnage and average grade from Oxide zone, 5.072 (Mt) and 0.423% respectively and the same from Haypvzhn zone, 60.59 (Mt) and 0.423% respectively. Then by assuming the grade block model as a constant value, a series of new economic block model was created by simulation of economical parameters such as price and costs with the use of the Monte Carlo method. Then pit limit for all simulation models was determined. Comparison between the estimated and simulated models revealed that the quantitative results of the risk. The results of Net Present Value (NPV), Cutoff grade and waste tonnage in final pit limit and Stripping Ratio (SR) from estimated model are lower than the simulated ones about 11.4%, 9.62%, 0.65% and 1.94% respectively. The NPV with 95% confidence interval varies between 3.57(Mt) to 4.56(Mt). But all mextal extracted from the Oxide and Haypvzhn zone, the revenue of pit limit, total extractable ore from Oxide and Haypvzhn of the estimated model are more than the simulated model about 0.2%, 1.73%, 2.17% and 1% respectively. The sensitivity analysis of NPV for economical parameters show that the most sensitive parameters are price product, annual discount rate and recovery of processing Oxide and Haypvzhn zone, and dilution is the least important parameter. The sensitivity analysis of cutoff grade of final pit limit revealed that price and costs are high sensitive parameters. With comparison of the final limits of simulated models with estimated model show clearly that the effect of the uncertainty in the economical parameters. Total extractable ore and average grade are 4.99 (Mt) and 0.399% in the final pit for Oxide zone respectively and the same for Haypvzhn zone are48.7 (Mt) and 0.439% respectively.