Aiming at the disadvantage of the high peak-to-average power ratio (PAPR) in asymmetrically clipped optical orthog-onal frequency division multiplexing (ACO-OFDM) systems in visible light communication, an improved discrete sine transform (DST) generalized precoding(DST-GP) method based on the GP method is proposed. In this method, the DST matrix, based on the GP method, is extended into an asymmetric matrix to obtain the better PAPR reduction performance, and then the calculation of the extended part is optimized by the GP method. The simulation results and analyses show that the proposed DST-GP method, compared with the original DST method, has a better PAPR reduction performance with the low cost and can achieve a better compromise between the PAPR reduction performance and the computational complexity.