The invention relates to a phase transfer catalyst for synthesizing benzaldehyde through oxidation of benzyl alcohol and a preparation method of the phase transfer catalyst. The method has the following steps: taking graphene oxide as a carrier, firstly immobilizing ionic liquid with a siloxane group on the surface of the graphene oxide through silylation reaction, and then immobilizing phosphotungstic acid on the surface of the silylation reaction through ion exchange reaction, so as to obtain the phase transfer catalyst. The catalyst has good catalytic performance in the application of phase transfer anticatalysis for synthesizing benzaldehyde through oxidation of benzyl alcohol, the conversion rate of benzyl alcohol reaches 91 percent, and the selectivity of benzaldehyde reaches 99 percent. The catalyst is simple in preparation process, high in phase transfer catalytic activity, and good in reusability, ensures that product aftertreatment is simple, and has a high application value.