The invention discloses a preparation method of clam essence. The preparation method comprises the following steps: soaking fresh and living clams which are bought in clean water so as to enable the clams to spit all soil in the clams; then adding pure water and the clams in the proportion of the pure water to the clams being 2:1 into a pot, and boiling the clams with slow fire; then cooling the boiled clams to a normal temperature; removing shells of the clams, leaving clam meat and juice, and crushing a mixture of the clam and the juice in a mixing machine into paste; adding flavored protease and papain for enzymolysis on the clams; raising the temperature to 95 DEG C, and performing enzyme deactivation for 25 minutes so as to obtain a clam extract; adding glucose, gourmet powder, salt and various amino acid to the prepared clam extract, and performing a Maillard reaction; and after the reaction, lowering the temperature, and adding compounded clam essence base so as to obtain the clam essence. The clam essence prepared by the preparation method disclosed by the invention is high in natural feeling, good in fidelity, attractive in flavor and rich in mouth feel, and freshness and fragrance of natural seafood, emitted from the clams, are more unique and attractive.