The use of a venturi tube to sustain the pipeline pressure in the dense-phase pneumatic conveying of pulverized coal system is promising for its application to the pressurized entrained-flow coal gasification process, in spite of the limited knowledge of the fundamentals of the gas-solid flow through the venturi tubes at high-pressure and dense-phase pneumatic transport conditions. In this paper, a series of experiments were carried out and the geometry parameters of the venturi tube, including the convergent angle, the throat diameter, the throat length and the diffuser angle were varied at constant flow conditions to evaluate their effect on the conveying properties and on the pressure reduction effects in the flow of gas-solid mixtures through the venturi tube. The optimum values or ranges of the above mentioned venturi geometrical parameters in the application of venturi tubes to dense-phase pneumatic conveying of pulverized coal are determined in this work. These values will provide a useful reference for the design of feeding systems in the pressurized entrained-flow coal gasification process. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.