Nitration of 4-methyl or 4-aminobenzoic acid was studied and two leadsaIts of aromatic carboxylic acids containing nitro groups were synthesized. It was found that nitration of aromatic carboxylic acids containing a strong electron donating group in the 2- or 4-position of the aromatic ring at 70～75℃ in sulfuric acid with excess of nitricacid gave trinitroproducts via IPSO nitration.