Relevance. Modern ways of upgrading drilling tools are aimed at obtaining designs that improve the quality of well drilling. At the same time, the geometry of the core tool should contribute to an increase in the core yield and maintain its integrity. The existing serially produced drilling tool allows achieving high indicators of the well construction, solving the problems of opening and sampling in sections with difficult drilling conditions. Thus, the design of the drilling tool with end flushing ensures the penetration of the cleaning agent directly under its working end without contact with the core, which helps to preserve the obtained mining and geological information of the sample. The use of such a drilling tool is most relevant when sampling soft, heavily destroyed or loose rocks. Given the specified area of use, the main disadvantage of the design of the flushing system of the tool with end channels is the high probability of their sludge contamination with the onset of negative consequences that reduce the technical and economic indicators of drilling and the potential of the tool. Thus, eliminating any possibility of clogging of the end flushing channels contributes to the implementation of the full-fledged operation of the tool. The work analyzes the hydrodynamic processes occurring in the flushing system of the tool and in the bottomhole zone of the well, which made it possible to determine the causes of channel clogging. The presented modernization of the tool geometry was made in order to eliminate the identified causes and improve the circulation of the cleaning agent. Aim. To develop a design for a flushing system for a drill bit with end flushing, providing optimal parameters of pressure and flow rate of flushing fluid in order to prevent clogging of the end flushing channels. Objects. Hydrodynamic processes occurring in the flushing system of a core drilling tool with end flushing. Methods. Analytical method, computer modeling method. Results. The paper presents a method for modernizing the flushing system of a diamond tool with end flushing. By creating favorable conditions for the flow of the cleaning agent by the proposed method the authors have solved the problem of slagging of the front channels of the flushing system located in the end part of the crowns and improved the cleaning of the tool working surface. The presented design of the flushing system of the crown allows fully implementing the functions of the cleaning agent without loss of hydraulic energy, and thereby improving the quality of well drilling and core sampling in loose, soft, easily destructible rocks. The effect is achieved by eliminating the zones of hydraulic resistance that occur at the junction of the structural elements of the drill crown.