The invention discloses a method for adsorption separation of an ionic liquid catalyst to reduce product acid value. The invention relates to an adsorption method for separation of a Lewis acid ionicliquid catalyst in a liquid chemical product, and the method avoids mass water washing and achieves the environmental protection purposes of reducing the chemical product acid value and avoiding wasteliquid generation. The method is characterized by effective separation of a small amount of Lewis acid ionic liquid catalyst in a liquid chemical product. Due to a small dosage, the Lewis acid ionicliquid catalyst can hardly reach effective recovery or separation by filtering, layering or other conventional separation methods. At the end of reaction, through a certain amount of an adsorbent, a liquid chemical product with low acid value and high quality can be obtained.