According to dyeing and printing wastewater of high chroma and difficult decomposition, a new ultrasonic focalize decomposition method is provide, which can decompose those are difficult to do. In this article, Dynamic adding-pressure dissolving-air, ultrasonic focalize and flocculate floating-air are assembled to advance the treatment effect. Through the research, the dynamic models of adding pressure and dissolving air and flocculate floating-air are constructed. Based on the theory research, a experiment device is designed. The effect and influence factors are discussed, which provides a new way to process dyeing and printing wastewater of high chroma and difficult decomposition.