For pray dust, multijet is better than single nozzle, however its internal structure and flow situation are more complex.Taking the German BAASMS11130° nozzle as example, the 3D modeling software CREO was applied to build its model, ANSYS ICEM was used to mesh it. Then ANSYS FLUENT software was used to carry on the numerical simulation. Changing the size parameters of nozzle, including the inlet velocity, inlet diameter, cyclone bore diameter and internal oblique angle, the number of cyclones and the main jet nozzle aperture and other parameters, the influences on the nozzle spray effect were analyzed.