Abstract: The in-situ stress parameters have become one of the most essential data for the stability design of a underground project, but there exist some misunderstandings on how to use in-situ stress measurements. Through analyzing the linear fitting plot of measured in-situ stress data versus depth, many problems can be found, such as scattered data, unstable correlation coefficient. Here, internationally-accepted Sheorey theory is introduced, which has taken the gravitational action, Poisson's effect, lithology and other factors into consideration, and this theory has defined one general variation law of the horizontal stress in the upper crust versus depth as well. One planned water-sealed oil reservoir is located in the Bohai Gulf, Liaoning Province. During the feasibility research stage of the project, hydrofracturing in-situ stress measurements have been done in two boreholes, but the measured data is scattered and hard to select one rational value for the design. By comparing the fitting effect based on the Sheorey theory with that of linear fitting, this theory can define the variation law of measured in-situ stress versus depth very well, and offer proper in-situ stress values for the project design. This method is of great significance to the design of other project.