The invention discloses a purifying method of N-vinyl-Epsilon-caprolactam, aiming to solve the problems of more process steps, difficult operation control and high requirement on the content of mother liquid in the traditional purifying method of N-vinyl-Epsilon-caprolactam. The purifying method comprises the following steps: A. crude distilling: directly carrying out reduced pressure distillation on N-vinyl-Epsilon-caprolactam reaction liquid to obtain an N-vinyl-Epsilon-caprolactam crude production solution; B. crystallizing and washing: adding the N-vinyl-Epsilon-caprolactam crude production solution obtained in the step A into a certain volume of water, reducing the temperature under the condition of continuously stirring for crystallizing, after sufficiently crystallizing, removing a water solution by filtration or centrifugal separation, and then adding water to wash; and C. distilling: carrying out reduced pressure distillation on the product obtained in the step B to remove water in an N-vinyl-Epsilon-caprolactam crystal, and then carrying out reduced pressure distillation again to obtain the N-vinyl-Epsilon-caprolactam with the content of at least 99.0 percent. In the method, an in-water crystallization method is adopted so that the method and needed equipment are simpler and are suitable for industrialized production of small and medium-sized enterprises.