At present paper, an ionic liquid (N-butyl pyridinium hexafluorophosphate, [BPy]PF6) that is liquid at room temperature and solid above 75°C was synthesized and the contents of ferulic acid (FA) at Angelica sinensis was determined after solid-liquid separation using [BPy]PF6 as the solid extractant by spectrophotometry. The results show that FA is extracted completely by [BPy]PF6 at pH 3.34 and [BPy]PF6 at FA can be stripped by 0.02 mol/L NaOH. The content of FA in commercially available Angelicae sinensis was 0.057%. The working curve, linear range, detection limit and recovery rate of FA were Y = 0.0732X + 0.054 (R 2 = 0.9995), 5.150×10 -3 -3.508 mmol/L, 2.870×10 -4 mmol/L and 90.5-109.5%, respectively.