The spectral modules of self developed radiometer are introduced. The spectral range covers the visible-short wave infrared band(400 nm~2 500 nm).The methods of opto-mechanical assembly of spectral modules are discussed and the results of opto-mechanical assembly are analyzed. The radiometer consists of three spectral modules: the visible spectral module(400 nm~1 000 nm)(VIS for short),the near-infrared spectral module(900 nm~1 700 nm)(NIR for short), and the short wave infrared spectral module(1 600 nm~2 500 nm)(SWIR for short).The detection units of spectral module use the flat-field concave grating to diffract and focus different wavelengths, use the linear array detector to detect signals.The optical units of spectral modules consist of optical fiber, slit, assembly of reflector, assembly of grating and assembly of detector. Since the effect of opto-mechanical assembly is closely related to opto-mechanical design, the result of opto-mechanical assembly can reflect the advantages and disadvantages of opto-mechanical design. According to the characteristics of the opto-mechanical design of the spectral modules, the opto-mechanical assembly was carried out. The results of opto-mechanical assembly show that the wavelength resolution of the three spectral modules is better than 4 nm, 15 nm and 20 nm, respectively. The design indexes of the spectral module are achieved, verifying the rationality of the opto-mechanical design.