Fluid flow metering device and method thereof

A fluid flow metering device and a method thereof are provided. The fluid flow metering device includes a fluid flow detector, a memory, a micro controller and a power generator. The fluid flow detector is disposed in a supply tube of a fluid flow provider. When the fluid flows in the supply tube, the power generator generates a supplying power through flow of the fluid, and provides the supplying power to the fluid flow detector, the memory and the micro controller. When the fluid flow detector detects the flow of the fluid, the fluid flow detector detects the flow of the fluid outputted from the supply tube to derive a detecting value. The micro controller receives the detecting value and writes the detecting value into the memory, or the micro controller converts the detecting value into a flow value and writes the flow value into the memory.