Agricultural water saving and irrigation water supply system, due to the different irrigate style, needs different water supply pressure. By installing energy dissipation and decompression equipment at some branch line of water supply, it could meet the pressure demand of different water saving and irrigation water supply methods. The energy dissipation equipment proposed made use of the orifice twisting to form the step and spiral-orifice which make the flow twist compulsively. As the flow twisted large angle in short distance instantly to form higher intensity spiral flow, the ratio of energy dissipation and decompression was higher, it could also be regulated in large range, so it could be used in agricultural water saving and irrigation water supply system and other similar piping system that needs energy dissipation.