Asymmetric modulation metamaterials enable advanced acoustic asymmetric focusing (AAF) effect, overcoming limitations in ultrasound therapy and imaging while enhancing acoustic communication and material processing. This chapter presents five innovative AAF lenses demonstrating multifunctional sound manipulation. A dual-layer metasurface design achieves AAF effects (2.91–3.61 kHz) through asymmetric phase modulation, with tunable focal positions. Another design using mode-conversion meta-atoms combines phase control and step waveguides for broadband (fractional bandwidth 0.19) subwavelength focusing (0.38λ). An underwater steel-plate lens (560–592 kHz) creates AAF via slit-induced interference, while a prism configuration with non-parallel interfaces achieves 0.36λ subwavelength focusing. Finally, a dual-layer phased array produces long-focus AAF (18.1λ) with 0.14 fractional bandwidth. These AAF systems address critical challenges in high-intensity focused ultrasound by preventing energy reflection damage, while offering precise focal control across different frequency ranges. The designs demonstrate exceptional versatility for medical applications including tumor therapy and ultrasound imaging, with additional potential in sonar and acoustic communication. By integrating asymmetric transmission with focusing capabilities, these metamaterial-based lenses establish new paradigms for acoustic energy manipulation in both therapeutic and diagnostic applications.