This paper proposes a method for air flow control of oscillating water column (OWC) wave power plants using fractional order PID (FOPID) controller. Due to high air pressure oscillations inside the OWC the Wells turbine often gets stalled which in turn reduces the power generated. Thus the air flow rate is required to be controlled via air control valves in order to achieve the desired electrical output power. The FOPID controller is used to control the electrical output power of the induction generator. Initially, the conventional PID controller has been designed followed by tuning of fractional parameters of FOPID using particle swarm optimisation (PSO). Numerical simulations show that the air valve control through FOPID has better response over PID control under different sea wave conditions.