Recently, due to high levels of air pollution, reducing particulate matter(particulates) is a social issue. Particulates emission from manufacturing industry accounts for 56% of total emission. NOx and SOx act as ultra-fine particulates precursor, that have conversion factor of 0.345 and 0.079 respectively. This micro-bubble system is hybrid system that operate as like scrubber, but different from conventional scrubber by using micro-bubble. Micro-bubble refers to a bubble with a diameter of 10um to 100um. When micro-bubble is destroyed, OH radicals are generated which can remove ultra-fine particulates precursor by oxidation-reduction reaction. Micro-bubbles have so small size that effective in eliminating ultra-fine particulates precursor due to its long retention time and high mass transfer ability. In this study, a pilot-size micro-bubble system (1290 x 392 x 4031, W x L x H mm) model was developed by using the Computational Fluid Dynamics (CFD). From this model, case study was conducted according to the flow rate of the flue gas. Micro-bubble formation varies with Reynolds number, optimization was conducted based on case data through gas-water flow analysis. This research is expected to meet the demand for decontamination technology based on the stance of strengthening regulation of air pollutants.