This paper presents a new design approach of a multi-nozzle etching process which is the core system for the production of a shadow mask. The shadow mask, which is a thin metal plate with a huge number of small holes in regular patterns, is a key component of televisions and computer monitors. The shadow mask plays an important role in controlling the definition, color and distinction of televisions and computer monitors. Thus, the development of a rigorous and systematic design method for a multi-nozzle etching process to manufacture the shadow mask is beneficial particularly from the viewpoint of increasing efficiency and improving productivity. The proposed design method is based on simulating the complex spraying pattern using a Monte-Carlo method, whereas a stochastic method, socalled genetic algorithm, is used for an optimization tool. In such a highly complex solution space, the genetic algorithm searches optimal solutions efficiently and effectively. The simulation of spraying pattern for the multi-nozzle system and the genetic algorithm are coded by C language, while the graphic representations are attained by MATLAB graphic tools.