The present disclosure provides a positioning adapter, a communication method, an indoor positioning system and an indoor positioning method. The positioning adapter includes: a first communication circuit, an encoder, a second communication circuit and an adaptation interface. The first communication circuit is configured to receive position information, and send the position information as well as identity information to the encoder. The encoder is configured to receive the position information and the identity information, obtain encoded information that matches the smart device by encoding the position information and the identity information, and send the encoded information to the second communication circuit. The second communication circuit is configured to receive the coded information and transmit the coded information to the smart device through the adaptation interface. The adaptation interface is configured to connect the positioning adapter with the smart device, and communicate with the smart device through the second communication circuit.