The invention provides an environment-friendly degradable food wrapper capable of realizing long-time whiteness retention and a preparation method thereof. The environment-friendly degradable food wrapper capable of realizing the long-time whiteness retention is prepared from refined and softened plant fiber, a microbial bacteria adsorbent, white vaseline, sodium alginate and nano titanium dioxide or nano zinc oxide. The preparation method comprises the following specific steps: removing pectin and impurities of plant fiber; performing gas explosion treatment with steam for refining; performing chemical pulping, and softening with a cellulase solution and a urea alkaline solution to form a pulp stock solution; adding the pulp stock solution into a solution containing the microbial bacteria adsorbent, and stirring uniformly; adding the white vaseline and a complexing agent to form bleached pulp; finally, adding the nano titanium dioxide or nano zinc oxide; mixing uniformly and concentrating to obtain the environment-friendly degradable food wrapper capable of realizing the long-time whiteness retention on a sheet forming machine. The food wrapper prepared by the invention does not contain a fluorescent whitening agent; through the methods of biological bleaching and inorganic bleaching, an environment-friendly degradable food wrapper capable of realizing the long-time whiteness retention and with delicate quality is prepared.