The invention discloses a tramadol multivesicular liposome and a preparation method thereof. The preparation method comprises the following steps of: 1, dissolving phospholipids, cholesterol and neutral lipids into organic solvents to obtain a mixture which serves as an organic phase; 2, preparing 10 to 500mmol/L tramadol solution which serves as an internal water phase; 3, adding the internal water phase with the same volume as that of an organic phase into the organic phase, and mixing and emulsifying the mixture to obtain water-in-oil primary emulsion; 4, preparing an external water phase containing amino acid and osmotic modulators and/or surfactants, and adding the external water phase of which the volume is 2 to 10 times that of the water-in-oil primary emulsion into the water-in-oil primary emulsion, stirring the mixture to form oil-in-water type double emulsion; 5, adding the emulsion into the solution of the amino acid, introducing nitrogen or carbon dioxide into the mixed solution to remove the organic solvent from the emulsion to obtain suspension; 6, dissolving the suspension into the solution of amino acid, centrifuging and taking lower liposome suspension to obtain the tramadol multivesicular liposome. The prepared tramadol multivesicular liposome has the advantages of higher encapsulation efficiency, good slow release effect, and longer analgesic effect.