Abstract This paper describes the design, calibration, and deployment of a sea color surface spectral radiometer that accurately measures downward visible wave (solar) irradiance and leave-water radiance. It is diffused on a moving platform, such as a ship on the sea for in situ measurements. The sea color surface spectral radiometer has two channels, one Self-Scanning Photodiode Array(SSPD), and its response wavelength is from 450 nm to 800 nm. As the instrument can detect two indispensable parameters––water-leaving upward spectral radiance and downward irradiance, we can compute remote sensing reflectance. It can provide sufficient irradiant data to meet the need of scientific study, promising it a bright application prospect. From the calibration and experiment results of the spectral radiometer, we can see the spectral radiometer is fairly accurate and the results satisfactory.