Method for converting estragole into trans-anethole

The invention relates to a method for converting estragole into trans-anethole. The method comprises the steps of carrying out isomerism reaction on the estragole and NaOH solution under pressurization so as to produce the trans-anethole, then carrying out acid pickling and neutralizing on the trans-anethole, washing, carrying out freeze crystalizing, centrifuging to separate, and vacuum rectifying to obtain the high purity trans-anethole with the purity of greater than 99.5%. The method has short reaction time, uses little alkaline, avoids contacting with the air, reduces side reactions like oxidative polymerization, improves the yield of the trans-anethole.