Disclosed is a pointwise scanning type micro-fluid metering device and a method thereof. The device comprises an N-way valve, a closed anti-corrosion fluororubber tube, a peristaltic pump, a fluid outlet, a control computing unit and two fluid detector Y1 and Y2, wherein for the N-way valve, 1-1 is an air port, 1-i are fluid inlets, and i is equal to 2 to N; the N-way valve is sequentially connected with the fluid detectors Y1 and Y2 through the closed anti-corrosion fluororubber tube the other end of which is connected with one end of the peristaltic pump with the other end connected with the fluid outlet; the control computing unit are respectively connected with the N-way valve, the fluid detectors Y1 and Y2 and the peristaltic pump.