Abstract: Disclosed is the use of chlorophyll dihydroporphin as a plant growth regulator. Compared with the prior art, a class of new type plant growth regulators are provided; since the direct decomposition product of chlorophyll is used as a product, the preparation and processing thereof are easier, the structure is relatively simple, and tedious reactions and preparations such as further chemical coordination/chelation/purification are eliminated, so that the product is more environmentally friendly and safer; the product has a better solubility than the corresponding metal chelate and has a more convenient method of use, making it more convenient to be used in the fields; the stability of the product has been improved, with stable quality assurance and a longer shelf life; the product has a natural source and uses a low amount of same due to a low effective dosage, thereby improving the utilization rate of silkworm excrement resources.