Abstract: The concrete filled steel tube (CFST) is increasingly widely used in bridge construction at home and abroad. The homogeneity control of concrete during the pouring is the key to ensure the good mechanical properties of CFST members. The distribution of various raw materials in the main concrete pipe directly affects the mechanical properties. In order to explore the distribution of the raw material in the tube during the pumping, the concrete slurry is equivalent to three phase material: air (phase 1), water (phase 2: liquid phase) and particle (phase 3: fake fluid). Through fluid mechanics software, the flow behavior and the volume distribution law of each phase were simulated when the tube was vertical layout and tilt layout. The pumping pressure with the height was also obtained. For the vertical layout, the second and the third phases of the concrete slurry shows the overall jacking at different speeds. As for the tilt layout, the second and the third phases rise along the ascending channel and sediment along the descending channel. The both arrangements will lead to the stratification near liquid level, and the sedimentation at the bottom. And the pumping pressure is proportional to the height. The above conclusions can provide a reference for the application of CFST in engineering.