Venturi device has important effect on pressure loss and flow field of flue-gas circulating fluidized bed desulphurization tower. Desulfurization tower is huge. Experimental study is difficult and costly. For these problems, PC-SIMPLE algorithm of Euler model of Fluent software is applied and flow condition of four different kinds Venturi tube are simulated in this paper. The pressure loss of curved Venturi is minimum. Three groups of Venturi tube can get uniform velocity field in the tower. Turbulence intensity of a group Venturi tube is maximum, followed by curved Venturi tube. But the turbulence intensity gradient of a group Venturi tube inside the absorber is also the largest. In order to get low pressure loss and better flow field, three groups Venturi tube is optimum.