Radio over Free Space Optics (RoFSO) is believed to be the most reliable technology in future communication as it provides high speed, high bandwidth and low consumption energy for data transmission. However, some turbulence weather factor such as fog, haze and rain may cause data attenuation in the FSO network. This project presents the effect of haze attenuation on RoFSO transmission system for Orthogonal Frequency Division Multiplexing (OFDM) modulation technique with Quadrature Amplitude Multiplexing (QAM) scheme. The data obtained was referring to the Air Pollution Index (API) from the region of Sepang, one of the town in Malaysia. The system is modelled and simulated using a software called OptiSystem. The result performance of RoFSO system when being modulated by OFDM is compared in terms of the BER value, received optical power and constellation diagram