Based on the efficiency model of the BUCK PFC(Power Factor Correction) LED(Light Emitting Diode) driver circuit, the theory analysis of the inductor optimal design is proposed in this paper, where the inductor operates in BCM(Boundary Conduction Mode). Considering about the frequency performance and EMI (Electro Magnetic Interference) of the driver circuit, the boundary condition of the frequency is given in the paper. The simulation and experiment results are presented to verify the theory analysis of the inductor.