Abstract: CoKriging combined with soft data can improve the accuracy of building geological model. By analyzing the reasons for the problems of the conventional CoKriging and collocated CoKriging, this paper deduces a new collocated CoKriging with soft data. The method uses the expected value of soft data in order to ensure the reliability of extrapolation, the use of the main variables filtered the expected value of co-observations to estimate parameters of variogram. The advantage of the new collocated CoKriging is that the interpolation reflects feature of main variable where the points are within the interrelated range of main variable, and the difference of interpolation comes from expect of each co-variable where the points are beyond the interrelated range of main variable. Finally, examples show the advantages of the new valuation method.