An improved Reed-Solomon coding based on channel-assisted power loading algorithm for intensity modulation and direct detection (IMDD) optical orthogonal frequency-division multiplexing (OOFDM) is experimentally investigated. A simple power loading algorithm based on channel characteristic is proposed to improve the performance of ordinary RS(896,832) method. This scheme is experimental verified by using a cost-effective and low-bandwidth Reflective Semiconductor Optical Amplifier (RSOA) based OOFDM system. Experiment results show that the FEC limit can be increased that give more BER tolerance for system design. We also notice that system performance can be further enhanced by interleaving input binary sequences.