Abstract: In consideration of inadequate research on photoelectric direct reading spectrometer used for steel detecting,we presented the Czerny-Turner system design method, discussed the optimization method and verifying method, as well as developed the spectrometer. It adopted cubic polynomial to fit calibration wavelength, and the tested resolution reached 0.225 nm in 436 nm~608 nm all band and 0.135 nm in mid band which could meet the demands of steel detecting. Furthermore, the qualitative analysis method based on multi-frame judgment guaranteed a 1.5% detective limit of 7 kinds of elements. The half quantitative analysis based on fitting spectrum database could offer 2% detective precision of the 25 kinds of samples. They could provide an important reference for the recognition of steel mark.