The aim of this work was to extend the shelf life of green vegetable and protect the quality of green vegetable. In simulated environment of the fruit and vegetable sales area in a supermarket, with fresh-cut broccoli as an example, low-density polyethylene films with different mass fractions (0.5%, 0.8%, 1.2%, 1.5%, 2.0%) of the mono-matrix double-function light conversion agent RBI were prepared. The gas permeability and optical properties of the light conversion films were tested. The LDPE films with different mass fractions of the mono-matrix double-function light conversion agent RBI were used to package fresh-cut broccoli, which were placed in a simulated supermarket lighting environment. The weight loss, and the change of vitamin c and chlorophyll contents in the samples were determined, and sensory evaluation was conducted for the samples. Compared with the existing green vegetable packaging film in the supermarket, LDPE film supplemented with a certain amount of light conversion agent could protect the quality of fresh-cut broccoli and prolong its shelf life. The low-density polyethylene films supplemented with 1.2% mono-matrix double-function light conversion agent had the best preservation effect.