The invention discloses a method for optimizing a visible light communication system with multiple light sources and multiple carriers under an unsmooth channel. The method comprises the following steps: (1) setting parameters of the visible light communication system with multiple light sources and multiple carriers, wherein the parameters comprise a channel parameter, a noise size and the maximum light power, and using the maximum data rate R as an optimization target; (2) optimizing DC bias b to obtain optimized DC bias b*; (3) optimizing a normalized beamforming vector {uk} to obtain an optimized normalized beamforming vector (the formula is as shown in the specification), k=1,..., K-1, wherein K is the total number of subcarriers; and (4) obtaining an approximately optimal beamforming vector omega* according to the normalized beamforming vector (the formula is as shown in the specification). According to the optimization method disclosed by the invention, the system hardware and other external conditions do not need to be changed, and the system performance can be greatly improved just by simple calculation; when the maximum light power of the system is limited, the optimized system light intensity can kept constant and can take lighting into account; and the optimization method disclosed by the invention is high in convergence speed, easy to implement and high in robustness.