Abstract: A novel method based on photorefractive (PR) two-wave mixing to detect air turbulence is presented. The air turbulence is modulated on the input pump and signal beams of a PR crystal, thus creating a phase fluctuation for the input beams. Such a phase fluctuation results in an intensity fluctuation in the output beams and the intensity fluctuation can be detected by measuring the differential signals between the two output beams. Our experimental demonstration shows that air turbulence can be detected effectively based on the process of PR two-wave mixing and an electrical differential detection. This method may be widely used in future detecting applications.