Abstract: In view of the existing demands and technical difficulties of pinpointing the location of in horizontal wells a new technology was proposed. This new technology uses the properties such as rare earth element abundance and inter-element γ peak interference. In this case, five neutron irradiation- generated isotopic markers that would not present naturally were selected, and a metallurgical process was utilized to form the solid marker with a certain porosity. Such marker was placed in a release device with the pressure-limiting open mechanism and conveyed to a horizontal well by tubing. By distributing the marker in different well sections, they were able to test the signal strength of different isotope markers in the produced fluid and determined the water producing location by analyzing the test data. The segmented water location technology by tubing conveyed marker for horizontal well was field tested in three horizontal wells, and the accuracy of water location reached 100%, which provided a reference for water shut-off and water plugging. Research and field tests showed that this technology overcame the shortcomings of existing water location technologies for horizontal wells, the water location string could be run in horizontal wells with complicated wellbore trajectories,. They were able to successfully complete the test and determine the water location in mechanically produced wells under production conditions. This technology had high accuracy of water location and could provide new technical means for accurate segmented water location in horizontal wells.