The invention discloses a degradable moisture retention mulching film and a method for preparing the same. Raw materials for the degradable moisture retention mulching film include chitosan, acrylamide, sulfanilic acid, aluminum oxide, tetrahydrofuran, polylactic acid, polyvinyl alcohol, polycaprolactone, polyethylene glycol, petroleum ether, low-density polyethylene, dodeca-carbon alcohol ester,traditional Chinese medicine extract liquid and nanometer titanium dioxide. The method includes steps of 1), preparing modified chitosan; 2), preparing modified polylactic acid; 3), adding the low-density polyethylene into the petroleum ether, stirring and dissolving the low-density polyethylene in the petroleum ether, then adding the dodeca-carbon alcohol ester and the modified polylactic acid into the petroleum ether, and carrying out heating reaction to obtain film coating liquid A; 4), adding the traditional Chinese medicine extract liquid and the nanometer titanium dioxide into distilledwater, adding the modified chitosan and the film coating liquid A into the distilled water, stirring the modified chitosan and the film coating liquid A to obtain film coating liquid B, manufacturinga layer of films on a smooth glass plate from the film coating liquid B by means of culturing and drying the films to obtain the degradable moisture retention mulching film. The degradable moisture retention mulching film and the method have the advantages that the degradable moisture retention mulching film prepared by the aid of the method is excellent in water absorption, moisture retention andbiodegradability, and environmental pollution can be prevented.