Abstract: The hydroxy and chlorine contents of a four functional epoxy resin, N,N,N',N' teraglycidy 4,4' diaminodiphenyl methane(AG 80), were determined by chemical analysis. According to the experimental results of the chemical analysis and the HPLC results reported in the literature, the concentrations of various impurities in AG 80 could be quantitatively given. ITis shown that the hydroxy and chorine contents especially the hydroxy contenTin AG 80 are higher , and the contents of epoxy group as well as TGDDM monomer in AG 80 are lower than those contents in other TGDDM epoxy resins in the world market. The experimental results show also that the main way to enhance the epoxy group contenTin AG 80 is to avoid the hydrolysis of the resin during its production process, and the measurements of the contents of hydroxy and chlorine in different forms in the resins are useful for the quantitative determination of various impurities in TGDDM epoxy resins.