Abstract: In order to accurately determine the parameters of the pressure measuring borehole drilling through seam, based on No. 15 seam gateway and the high I evel gas drainage gateway in Hongyuan Mine as a prototype, the geometrical model of the pressure measuring borehole drilling through the seam was established. Acc ording to a space layer relationship between the pressure measuring borehole drilling through the seam and the inclined seam in the model, the paper discussed a false inclination affected to the calculation of the borehole length and a geometrical formula to calculate the borehole length and the rock borehole length was obtained. Base d on an Excel data processing software, a program to calculate the length of the pressure measuring borehole drilling through the seam was compiled and written.The P rogram found that the error between the theoretical length and the actual length was less than 1 m. The accuracy of the calculation formula was verified and the applica tion of the calculation formula could improve the design efficiency and the site construction accuracy.