The utility model discloses a photinia serrulata blade red degree measuring device which comprises a bottom plate, a perforating plate and a color comparing card. An observation hole is formed in the middle of the bottom plate. A perforating boss is arranged on the perforating plate. The size of the observation hole is matched with that of the perforating boss. The observation hole is a litter larger than the perforating boss. The color comparing card is located under the bottom plate and observed through the observation hole. A photinia serrulata blade is taken and placed on the bottom plate, the perforating plate covers the bottom plate, the perforating boss presses the blade on the observation hole to form a hole equal to the observation hole in size, the perforating plate is moved away, the color comparing card moves back and forth under the bottom plate, the color of the color comparing card and the color of the blade are observed through the observation hole, and when the color comparing card is moved to be proximal to the color, a mark on the color comparing card is read and is the color level of the blade. The measuring device has the advantages that the color level of the blade can be detected fast and accurately, influence of the external environment is avoided, and the measuring device does not generate errors easily.