Abstract: In order to find out whether the trajectory of radial well branch in coal seam is consistent with the design scheme to ensure the effect of permeability enhancement and reservoir reconstruction by radial well, by means of the combination of small-scale surface and field test, the influencing factors of radial well trajectory in coal reservoir were firstly studied. Based on the principle of the potentiometry monitoring technology, the feasibility of this method for the radial well trajectory monitoring was analyzed. On this foundation, the monitoring method and the technology of coal reservoir radial well tra-jectory based on potentiometry was established, and the field monitoring analysis was carried out. The results show that the trajectory of radial well in coal seam is mainly controlled by the original fractures, ground stress, weak structural surface and other factors. In the process of jet, the borehole azimuth usually deflected in different degrees, and the angle was between 15° and 30°. The branch injection length of radial well was also shorter than the designed one. The change of radial well trajectory parameters, such as azimuth and length, could be monitored clearly by potentiometry. The research results could effectively guide the design and construction of the radial well in coal reservoir.