The invention discloses a synthetic method of taurocholic acid. The method comprises the following steps: A, mixing and stirring cholic acid with acetone and cooling to -10 to 30 DEG C, adding organic alkali, dripping ethyl chloroformate below 30 DEG C after evenly stirring, reacting for 1-3 hours after dripping is finished, and filtering to obtain filtrate; B, adding the filtrate in the step A to a solution formed by taurine and water, adjusting the pH to 7-11 by using organic alkali, then reacting at 20-30 DEG C for 3-5 hours, and filtering to obtain filtrate after reaction is finished; C, adjusting the pH of the filtrate in the step B to below 1 by using 10-30% of hydrochloric acid, concentrating in vacuum at 40-65 DEG C to dry, adding methanol, heating for dissolving, adding acetone to evenly stir, and cooling to -5 to 0 DEG C for crystallizing; filtering after crystallization is finished; washing a filter cake by acetone, draining and drying in vacuum. The invention aims at providing the synthetic method of taurocholic acid, which is simple in technology, relatively low in production cost, high in yield of taurocholic acid, and convenient for industrial production.