The invention relates to the technical field of integrated circuit IP core design and provides an I3C device and a communication method. The I3C device comprises a client, an I3C master device and a slave device, wherein the slave device comprises an I2C slave device and/or an I3C slave device, the I3C master device is connected with the I2C slave device through an I3C bus, the I3C slave device isconnected with the I3C master device through the I3C bus, the client is used for sending a control command stream to the I3C master device and receiving a feedback signal fed back by the I3C master device, the I3C master device is used for receiving the control command stream, analyzing the control command stream into a bus control signal and sending the bus control signal to the I3C bus, the I2Cslave device is used for receiving a bus control signal, corresponding to an I2C specific address, on the I3C bus and receiving data sent by the I3C master device, and the I3C slave device is used for receiving a bus control signal, corresponding to an I3C address, on the I3C bus and receiving the data sent by the I3C master device. Through the I3C device and the communication method, the advantages of an I3C norm can be reserved when the I3C master device is compatible with the I2C slave device, so that communication with the I3C slave device is performed at a high data rate.