The phenomenon of competitive water use generally exists in various aspects of water science research and water management practice. Systematic understanding and reasonable resolution of competitive water use issues are significant for ensuring national water security in the new era. Based on the accumulated research on competitive water use, the concept of competitive water use is defined for the first time, its connotation is interpreted from the three dimensions of time, space and system, and its types are classified. Accordingly, a three-dimensional hierarchical structure of 12 types of competitive water use is constructed. Then, the essence of different competitive water use issues is analyzed, and the basic principles that should be followed to solve these issues are summarized. On this basis, the potential solutions and related methods for different competitive water use issues are further explored, and a general calculation method for competitive water use is proposed systematically. A case study of the Yellow River water allocation problem is carried out, and an integrated water allocation scheme with a total volume of 370 m³ is obtained for the Yellow River.