In order to improve the atomizing performance and decrease the consumption, the effect of air flow and water flow on the atomizing characteristics of twin-fluid impact nozzle was researched, the twin-fluid atomizing flow field was tested under different working conditions by an open atomizing test bench which was based on phase Doppler particle analyzer (PDPA). The atomizing characteristics which included spray cone angle, atomizing range, droplets diameter distribution, droplets velocity distribution and droplets numbers distribution were analyzed systematically according to the test results. It could be concluded from the test results, with the increase of air flow and decrease of water flow, the spray cone angle was increased remarkably, the droplets Sauter mean diameter (SMD), droplets velocity and droplets numbers were decreased, but the atomizing range showed an increasing trend with the increase of air flow and water flow. The distributions of droplets SMD, droplets velocity and droplets numbers were increased along the axial direction. Moreover, the distribution of droplets SMD was increased while the droplets velocity and droplets numbers were increased firstly and then decreased along the radial direction. Furthermore, the turbulence and hedging in the region between the nozzle exit and vibrating head were affected obviously by the air flow and water flow, and then the atomizing characteristics was markedly influenced. The air flow and water flow were decreased by 15.79% and 12.50%, respectively, after optimization when they were 0.8m3/h and 35L/h, meanwhile, the SMD was decreased by 21.50%, the atomizing range was increased by 10.26%, the droplets velocity and droplets numbers were increased by 39.08% and 61.54%, and it can be concluded that the atomizing performance was improved and the consumption of the nozzle was decreased.