The new nanosolid superacid catalyst TiO2/SO42- was prepared by sol-gel method, and samples were characterized by acid base titration,XRD and TEM. Results show that the superfine solid TiO2/SO42- is nanocrystal with good dispersibility and its average size is 27 nm. With the catalyst TiO2/SO42-, 2,4,N-trinitroanilinoacetic acid(TNAA) was synthesized from chlorobenzene and glycine with yield of 71.6%. The optimum conditions are 0.2 mol chlorobenzene,and 0.7 g catalyst,and 0.07 mol glycine,and 0.08 mol nitric acid,and reaction time of 3 hours,and reaction temperature of 45 ℃. When calcined at 600 ℃,the activity of regeneration catalyst is restored mostly after regenerated eight times.