The invention discloses a method for conversion and synthesis of phenyllactic acid by using microorganisms, and belongs to the technical field of biochemical engineering synthesis. According to the method, phenylpyruvic acid is used as a key substrate, lactobacillus buchneri thalli which are subjected to freeze-thawing permeation processing serve as a whole-cell catalyst, and conversion and synthesis are carried out under a certain temperature condition so that the phenyllactic acid can be obtained. By the adoption of the method, the conversion yield of the phenyllactic acid under the optimization condition can reach 91%, and the concentration of a phenyllactic acid product in a conversion solution can reach 11 g/L. Strains used in the method are safe microorganisms which come from food, and the permeation processing is simple, convenient, safe and free of toxicity. The conversion process of the microorganisms is small in number of steps, short in time, low in cost and high in conversion yield. Safe and quick synthesis and preparation can be achieved, and the method has a broad application prospect in the field of phenyllactic acid preparation.