The purpose of this researchis to find out the characteristic of reservoir parameter and to estimate the pressure of geothermal from a new well in the Kamojang geothermal field. The Annealing simulation method is a conditional simulation that has some advantages is able to avoid local optimal value mistake and can be used in data extrapolation.The results of the annealing simulation on the geothermal field are image contour and semivariogram of parameter reservoir. There are two conclusions gained from this research. Annealing simulation method gives an image of reservoir with limited data and is valid to be used in parameters prediction of reservoir at the Kamojang geothermal field with significance 5% and the optimum pressure of geothermal is 31.85 ksc wirh location (-22248m 1663.6m).