Embodiments of the present invention provide a method and system of encryption, decryption, and encryption and decryption based on visible light communication. A transmit end performs a logical operation on an original data signal and a pseudocode signal varying with a unit interval to obtain a scrambling code signal, and sends the scrambling code signal in a form of a visible light signal. A receive end receives the visible light signal sent by the transmit end, and converts the visible light signal into a digital signal; and decodes the digital signal and a pseudocode signal varying with a unit interval, so as to obtain the original data signal. The visible light signal transmitted between the transmit end and the receive end is not original data, but a scrambling code signal varying with a unit interval, thereby improving security of the photonic Internet of Things.