Abstract: During the general exploration work of Yaogou copper deposit in Xunyang Country, Shaanxi Province, it's found that the assessment of ore deposit's reserves and ore bodies' quality is unreliable, due to the developed faults in the field, complex stratigraphy, diversified types of mineralization,ore fabricand wall rock alteration, high discrete degree of ore quality aswell as ore body shapes.Meanwhile, combing with the current problems about stability and reliabilityof quantitative analysison reserve estimation based on the standards of solid exploration, aprobability statistics method has been proposed to evaluate the trend analysis and reliability of deposit's reserves.Stability index-β is calculated by reserves divisors product,and the stability of deposit's reservesis analyzed by β-n curve of ore grade, and then the criteria of reserves stability analysis has been proposed in this paper.Stability of ore quality is analyzed by the distribution trend of p-n curve,which serves as the analysis criterion of quality stability. The reliability of reserves is show as comprehensive value of reliability, which is judged by intersection between the stable tendency of reserve factors and frequency of ore grade.This paper aims to finding out a widely suitable method to identify the relibility of reserves(quality) by inductive method, which has been applied to Yaogou copper deposit. This method plays an important role in the stable tendency evaluation of deposit's reserve, providing evaluation criteria for stability analysis of mineral deposits with various types, especially for endogenetic metal deposits and hydrothermal metasomatic deposit.