Reservoir capacity is closely related to the effective thickness of the reservoir, permeability, porosity, saturation and resistivity. At present, the method to predict and evaluate tight reservoir can be rarely used. Comprehensive Productivity index is a research method to predict productivity based on the combination of logging and testing date. This method applied is stronger. The method of comprehensive productivity index is selected of the better formula of correlation coefficient based on the relationship between the combination of five parameters (the effective thickness of the reservoir, permeability, porosity, saturation and resistivity) and the different relationship of productivity index . In this paper, to predict reservoir capacity through the comprehensive arrangement analysis on tight reservoir data in Karamay Oilfield based on the method of Comprehensive productivity index. In real application, we need to choose one of methods to establish the relationship between Comprehensive productivity index and Productivity index in order to predict Productivity effectively. The results show that the method is not only reasonable and practical, but also has certain guiding significance to the exploration and development of tight reservoir.