Abstract: The gas flow filed in the circulation gas-water atomization is simulated by using the computational fluid dynamics software Fluent, and the effect of different distance of inlet pipe on the gas flow filed is analyzed. Results show that the gas velocity increases to the maximum value at the circular seam and decreases with the farther spraying distance. The gas of inlet pipe flows back when the extending length of inlet pipe is shorter than 5 mm, which leads to the failure of atomization for the device. The value of negative pressure on outside of inlet pipe decreases with the increase of extending length. Considering the negative pressure and recirculation zone, the extending length of inlet pipe should be 5 to 6 mm.