With the application of directional drilling technology more and more widely， the control technology of borehole trajectory becomes particularly important. In order to study the natural bending law of the borehole， find out the change trend of the vertex angle and azimuth angle， and then predict the change of the borehole trajectory to be drilled， use SPSS software to conduct multiple equation regression statistical analysis on the borehole inclinometer data of Anhui No.1 mining area. On the basis of considering the influence of the hole depth and the spatial location information of the hole opening point （x、y、z coordinates） on the vertex angle and azimuth angle， a quaternion octave polynomial regression equation is established， and the average angle full distance method is used to compare the spatial location of the regression fitting borehole axis with the actual borehole spatial location. The results show that after linear processing of the original drilling data， a good result can be obtained by using quaternion octave polynomial regression. If the regression is carried out after classification according to the different occurrence of the stratum where the drilling is located， the fitting degree will be further improved. The regression equation with high fitting degree can be used to predict the natural bending trajectory of the borehole in the non-perforated area， which also plays a good role in controlling the borehole trajectory in the project construction， and can better guide the project construction.