Modeling and ore reserve estimation are very important in excavation designing of any mine. Thus, description and evaluation (quantitavely and qualitatively) of ore body for Mining Engineer is a vital task. In this research, the results of modeling and reserve estimation of Janja copper mine are presented through implementing a geostatisitcal modeling. For this purpose, DATAMINE software is utilized. In the first step, using information such as exploratory data, geological sections, and so on, the border of sought target is created and then is discretized into smaller blocks considering dip and direction of the layer. In the next step, statistical and geostatistical analysis on the drilling data is performed to estimate the grade of blocky model using kriging. After cross validation of the results, the amount of the resource is determined.