A process for preparing a polyether ether ketone. Sodium carbonate is used alone as the condensation agent, and 4,4′-difluorodibenzophenone, p-benzenediol and biphenyldiol are subjected to polymerizing. After the corresponding prepolymer is obtained, the reaction temperature is elevated and p-benzenediol is further added as a chain extender to react for a period of time to produce high-viscosity polyether ether ketone.