The invention relates to a light-blocking PE (
polyethylene) film for 
food packaging, which is used for packaging food. Through the addition of 
riboflavin as a 
photosensitizer to PE master batch, the blocking performance of the PE film to the illumination at a specific 
wave band, the contact between the illumination at a specific 
wave band and the PE film is blocked, and the illumination oxidation of the packed food is retarded. A preparation method of the light-blocking PE film comprises the following steps: (1) mixing the PE master batch and 
riboflavin, placing into a double-roll plastic mixing mill for plastication, wherein the 
extrusion temperature is 130-140 DEG C; (2) placing extruded stock in the middle of two independent press plates, placing the press plates into a press vulcanizer, prepressing at a 
hot pressing temperature of 155-165 DEG C under a 
hot pressing pressure of 0.4-0.6MPa for 3-4min to melt the extruded stock, and uniformly distributing the melted extruded stock into the press plates; and (3) setting the pressure of the press vulcanizer to 10-11MPa, keeping 
hot pressing for 3-4min, taking out the press plates, placing into a pressure forming 
machine, and pressing under a pressure of 4.5-5.5MPa at 
room temperature for 5-6min. Through the addition of the 
photosensitizer riboflavin to the PE master batch, the absorption performance of the PE film to illumination is improved, the contact between the illumination and the packed food is blocked, and the illumination oxidation of the food is retarded.