An optical communication device, an optical communication system, and a method for establishing a communication connection are provided, relating to communications technology. In the optical communication device, the first driving circuit can control, based on the generated first target plaintext, the optical signal transmitting circuit to transmit the first optical signal, and control, based on the generated first key, the optical signal transmitting circuit to transmit the second optical signal. That is, an optical communication device that detects the optical signals can establish, based on the optical signals, a communication connection with the optical communication device that transmits the optical signals.