The invention discloses a preparation method of trepang oral liquid without fishy smell. The preparation method comprises the steps of removing substances with fishy smell, such as urea, amine and low molecular acid, by adopting a boiling water scalding method, smashing trepang, then adding papain, compound protease and gingerol for mutual enzymolysis, enabling components with fishy smell, such as aldehyde and ketone, to make oxidation reaction, aldolization reaction or esterification reaction, so as to weaken peculiar smell, adding extracting solutions of apple and hawthorn into obtained enzymatic hydrolysate, neutralizing substances with fishy smell, such as methanthiol, by using organic acid in the extracting solutions, and then seasoning by using extracting solutions of medlar, momordica grosvenori and corn. The method is simple, the effect is remarkable, effective components of a product are not affected, most substances with fishy smell are removed, and the oral liquid is better in mouthfeel and low-cost, and meets the requirement of large-scale production.