Abstract: The trajectory prediction technology of directional drilling in coal mine is foundation to realize the borehole trajectory intelligent control. Through studying the deflecting law of directional drilling in coal mine, tool face angle is the main factors of the screw drill to change drilling track. It builds the mathematical model that tool face angle changes the borehole trajectory by inclination and azimuth angle, and derives the prediction algorithm of directional drilling trajectory for tool face angle, and develops a corresponding software of the directional drilling trajectory prediction. Finally the Yangliu Coal Mine test shows that the drilling trajectory prediction software can meet the construction accuracy (the relative error is less than 1.38%), drilling tool frictional resistance decreases more than 20%, which improves construction safety of directional drilling.