Objective: A new method for extraction and separation of catalase from tomato was established based on a new ionic liquid of 1-hydroxyethyl 3-methylimidazolyl Fe3O4 nano-magnetic fluid. Methods: The effects of ionic liquid dosage， extraction temperature， extraction time and other parameters on catalase activity were investigated. Results: The optimal extraction conditions obtained by response surface experiment were as follows: the optimal amount of 1-hydroxyethyl 3-methylimidazolidyl Fe3O4 nano-magnetic fluid was 176 mg， the extraction temperature and the extraction time were selected as 35 ℃ and 30 min， respectively. The comparison of the catalase activity of tomato samples between the optimal and traditional extraction conditions in experiment， where showed the higher enzyme activity applied ionic liquid extraction based on magnetic nano materials， and the extraction time was shrunk by ten minutes. Conclusion: in this work， an efficient extraction method of hydrogen peroxide and other enzymes wasstudied.