Abstract: A detailed study is performed for the decomposition of simulated wastevitrification glass formed specimens which contain not only the main compo-nents of glass (B, Si, Na, etc.) but also the elements existing in the HLLW, suchas fission products, corrosion products (Zr, Ti, R.E., Fe, Cr, Mn, etc.).The glass specimens can be decomposed thoroughly by LiBO_2 fusion method.Since glass is of large molecule arranged without order and noncrystal in struc-ture, the amount of flux with two times that of specimen is enough for its decom-position. The decreasing amount of flux is advantageous for eliminating theblockage of nebulizer and the requirment for purity of the flux reagent is notso strict. The LiBO_2 fusion method for decomposition of glass specimens is verifiedby using of the certified glass standard 75-1.