In this thesis work, a coupling method of computational fluid dynamics (CFD) and discrete element method (DEM) is successfully applied to simulate the process of hydraulic conveying. The fundamentals governing the complex liquid-solid flow and performance of hydraulic conveying are systematically analysed in terms of particle-particle, particle-fluid and particle-wall interaction. The flow regimes and their transition, solid pattern, and pipe wear under different geometrical, operational and material conditions are carefully examined. This study would provide important suggestions/guidelines for the design and control of hydraulic conveying systems.