The present invention relates to hydraulic engineering, and particularly, to an apparatus for measuring the fluid velocity and flow rate of running water in a river, lake, sea, and the like. Particularly, the present invention relates to a system for measuring fluid velocity and flow rate and to a method for measuring same, wherein the system comprises: a plurality of floats (100) simultaneously dropped into running water to transmit GPS position information signals on a real-time basis; and a receiving station (200) which receives, on a real-time basis, the GPS position information signals transmitted from the plurality of floats (100). The plurality of floats (100) are divided into two or more sets (100a, 100b, 100c) in accordance with communication frequency bands (F1, F2, F3), and at least one of the sets (100a, 100b, 100c) consists of two or more floats (100) which use the same communication frequency band (F1, F2, F3) and which in turn transmit GPS position information signals.