Pyromellit-tetra-diethanol amine (PTDA) was synthesized with pyromellitic dianhydride (PMDA) and diethanol amine (DEA) as raw materials. Multi-benzene dendritic Molecul（PTDA-3,5-DAC）was prepared PTDA using 3,5-dihydroxybenzoic acid(3,5-DAC) modifying PTDA. Its structure was identified PTDA means of FTIR and NMR. In the energy transfer systems of PTDA-3,5-DAC and fluorophores (Eosin B, Rhodamine B, Titan yellow and Methylene blue), the changes of fluorescence intensity were studied. The results showed that the optimum conditions were determined as following: reaction temperature was 160 ℃, reaction time was 4 h, catalyst dosage was 2.0 %, catalyzer was toluene sulfonic acid. The extent of reaction is 75.67 %. The fluorescence of fluorophores decreased when PTDA-3,5-DAC was added into Eosin B' and Methylene blue' DMF solutions. The fluorescence of fluorophore increased then decreased when PTDA-3,5-DAC was added into Rhodamine B' DMF solution. The fluorescence of fluorophore lesser increased when PTDA-3,5-DAC was added into Titan yellow' DMF solution.