The invention provides an automatic identification passive tag based on 
visible light communication and a communication 
system thereof. The passive tag comprises a photocell, a tag 
chip connected with the photocell, and an LCD (
liquid crystal display) screen connected with the output of the tag 
chip and used for emitting optical signals. The communication 
system comprises the automatic identification passive tag used for receiving light emitted by the reader-writer and reflecting information of itself to the reader-writer. A light-emitting component for emitting light to the automatic identification passive tag in the reader-writer is a light-emitting 
diode; and a receiving portion for receiving the optical signals reflected by the automatic identification passive tag in the reader-writer is a photoelectric 
detector. The automatic identification passive tag and the communication 
system have the advantages of bidirectional 
visible light communication and having a storage function; 
visible light communication light resources can be utilized to provide energy for an RFID (
radio frequency identification) tag to realize passive work; and meanwhile, the automatic identification passive tag and the communication system also have the 
advantage of electromagnetic-
radiation-free 
optical communication. The tag is long in service life, is free of 
cell replacement, has the functions of storage, data modification, 
reusability and 
high security, and can serve as an 
upgrade product of a paper-based tag.