In this Letter, a novel five-dimensional (5D) data-iteration-based encryption model is proposed at physical layer for multi-wavelength optical frequency division multiplexing passive optical network (OFDM-PON) by using a hyperchaotic system. The proposed scheme can generate five chaotic sequences at a time. The sensitivity of 10-18 can be achieved, along with a key space of 1095. In addition, we use a multi-wavelength channel to transmit the information, and the optical network unit can freely choose the wavelength. The probability shaping technology has greatly improved the bit error rate performance. A 16Gb/s/λ data is successfully transmitted across 25 km standard single-mode fiber in the experimental verifications. Therefore, it will have a positive impact in the future security optical network.