The "GFS high-reflectivity measuring instrument" used in the visible and infrared regions are developed. According to the measuring principle of double-reflectance on a sample, the instrument takes a simple structure of a single optical path. The optical signals are investigated by statistical counting with a current-frequency oonvertor. The electric elements involved are all made in China. A high stability and linearity are realized in optic-electronic detection and readout. We take some measures to reduoe the systematic errors of the instrument. The measurement accuraoy has been analyzed and tested. The results show that the measurement accuraoy ies are better than ±5X10~4 in the visible region; and ±1Xl0~3 in rear infrared region.