To meet the requirements of outdoor field mineral analysis and remote sensing ground verification spectral analysis, the wide-range fiber spectral instrument covering 400 nm-2 500 nm was developed. The present article illustrates the design of the optical, mechanical and electrical parts of the instrument. The optical system utilizes grating horizontal-reflecting light route to implement the full coverage of the spectrum. Three line-array sensors are intercrossed in three directions on the spectrum surface to sense different spectrum ranges. CPLD device generates the sampling and driving temporal logic signals to the three line-array photoelectrical devices. Fourteen bits high speed AD converts the analog signals into digital ones. USB 2.0 is used for communication. The final results demonstrate that while implementing the measurement of wide spectrum, the instrument is improved in size, spectrum resolving power, signal quality and measuring speed. Ideal spectrum data were acquired.