In order to solve the problem of serious impact on the workshop staff and the surrounding residents caused by the strong noise generated in the process of external blow ring blowing surplus Zinc (Zn) particles in the hot-dip galvanizing workshop, the external blow ring nozzle is optimized and modified. A semicircular outlet groove was added on the original slit nozzle. In addition, combined use with Large Eddy Simulation (LES) and FW-H equation, the sound field characteristics of external blowing ring were analyzed before and after modification. The results show that the noise at the center of the exit of the original outer ring nozzle reaches 121 dB at the maximum. When the increased number of semicircular grooves is 30 and the diameter is 1 mm, the maximum noise of external blowing ring after the modification is reduced to 85.7 dB. In order to verify the correctness of the numerical simulation results, the external blow ring noise before and after the modification was measured experimentally, which shows good noise reducing effects after modification.