Oxygen is one of the most important factors to promote browning of fresh cut fruits and vegetables. Therefore, fresh cut fruits and vegetables must be blocked as far as possible when they are packed. The application of biomaterials to existing packaging materials can greatly increase the oxygen isolation performance of packaging materials. Cellulose nanocrystals/chitosan oxygen free coating materials were prepared by coating different pH chitosan and nano cellulose coating solution on the non crystalline polyethylene terephthalate (A-PET) film. The coating process and the thickness, shape and oxygen isolation effect of the film were systematically evaluated. The results showed that the coating process adopted in the experiment was relatively stable, and the thickness of the composite film produced by different layers had a significant positive linear correlation with the number of layers of the composite coating. The composite coatings with different thicknesses can be obtained by repeatedly repeating coating layer coating. And the coating effect of CS(pH4)/CNs(pH2) combination was better than that of CS(pH2)/CNs(pH6) combination. The combination of composite membrane oxygen barrier performance test results showed that with the increase of the number of coating, the oxygen barrier performance of the composite membrane was improved continuously. However, the oxygen barrier coefficient of the composite membrane was not obviously decreased after coating to the tenth layer. Four kinds of coated oxygenbarrier films with the number of coating of 5, 10, 15, and 20 were selected to preserve freshcut apples and stored at 4℃ for 4d. Compared with the oxygen-free membrane without coating, the brightness value of oxygenbarrier composite membrane with 20 coating layers was increased by 10.8% on the fourth day, and its nutritional content indexes of titratable acid, vitamin C content and soluble solid content were increased by 1.08 times, 23.8% and 28.6%, respectively.