The invention discloses a multi-user sending precoding design method in visible light communication, and belongs to the field of wireless optical communication. According to the method, the nonlinearity and illumination requirements of the LED are comprehensively considered, and a multi-user sending precoding algorithm under optical constraint is established, so that multi-user interference can besuppressed while the expected indoor illumination level is kept, and the method is more suitable for being applied to a multi-user visible light communication system. According to the method, optimalsending precoding conforming to actual constraints is formulated, the purpose of maximizing the minimum signal-to-interference-plus-noise ratio between users is achieved, and compared with a traditional zero-forcing algorithm based on pseudo-inverse, the method has obvious performance gain; furthermore, due to the fact that the multi-user precoding sending design problem in visible light communication is quasi-convex, the optimal solution of the precoding sending matrix can be effectively obtained through the dichotomy, meanwhile, the direct current bias voltage needed by the expected dimminglevel is obtained, and the dimming control function is achieved.