A novel Keggin heteropolyacid anionic Brϕnsted acid salt [(CH₂)₄SO₃HMim]H₂PMo₁₂O₄₀ was synthesized and used as catalyst in toluene nitration in HNO₃(67%) with good catalytic activity. With the molar ratio of toluene to nitric acid 1:3, catalyst to toluene 1:10, and reaction for 10 h at 50 ℃, the yield of mononitro products is about 84.9%, and the ratio of ortho-to para-isomers about 1.21.