The monochromatic synchrotron radiation spectra of spherical grating monochromator (SGM) working in soft Xray and vacuum ultraviolet (VUV) region are often contaminated by significant amount of higherorder harmonics. They cannot be suppressed completely even by suitable filters. Higherorder contributions in the spectral radiation standard and metrology beamline are researched by using transmission grating (3300 lp/mm made in house) and IRD AXUVI00G (USA) photodiode detector. The exit beam is dispersed with the transmission grating behind exit slit of the monochromator, and the contributions of the different orders are analyzed. In wavelength region between 5 nm and 34 nm with proper Al, Si and Zr filters, the contributions of higherorder intensity are less than 8.06%. After modified by quantum efficiency of the detector, the higherorder contributions are restricted to less than 3.08%. In wavelength region between 35 and 40 nm with Al/Mg/A filter, the higherorder contributions are restricted to less than 10.00% after modified by quantum efficiency of the detector.