Cross Section Gas Holdup Distributions at 3/4 Dimensionless Static Liquid Height in a Gas-Liquid Stirred Standard Rushton Tank Were Measured using 137Cs Γ-CT Scan Measuring Technology at Larger Gas Flow Rates and Higher Impeller Rotating Speeds. the Obtained CT Scan Images and Digital Distribution Curves of Gas Holdup with Dimensionless Radius based on the CT Images Could Explain the Fluctuation Changes of Gas Holdup Distribution. the Dense Area of Gas Holdup Distribution Appeared in the Upper Space of Impeller Blades. Gas Holdup Increased Both with Gas Flow Rate and Impeller Rotating Speed, But Gas Flow Rate Had More Influence on Gas Holdup Than Impeller Rotating Speed. the Eulerian-Eulerian Two-Fluid Model Coupling with the Bubbles' Coalescence and Break-Up Models, and the Drag Coefficient Model Were Established to Make CFD Simulation of Gas Holdup Distributions for the Gas-Liquid Stirred Rushton Tank under Different Gas Flow Rates and Impeller Rotating Speeds. © 2011 Elsevier Ltd.