Embodiments of the invention disclose an underwater visible light communication method and system. The method comprises the following steps of obtaining an impulse response function of an underwater channel used for transmitting a signal; sampling the impulse response function to obtain a channel characteristic matrix; modulating a to-be-transmitted signal to a plurality of subcarriers through inverse fast Fourier transform (IFFT) and splitting each modulated subcarrier into a plurality of signal blocks; determining zero fill quantity according to sampling quantity of the impulse function and carrying out zero fill processing on the end of each signal block according to the zero fill quantity; making the signal blocks subjected to zero fill processing form serial data and sending the serial data to a light signal source to generate a visible light signal; generating an electric signal according to the visible light signal and carrying out zero-forcing equalization processing on the serial signal according to the channel characteristic matrix; and carrying out fast Fourier transform (FFT) on the signal subjected to the zero-forcing equalization and restoring the to-be-transmitted signal. The method and the system can both consider the communication efficiency and quality and have wide application prospect.