The invention provides a device and a method for adjusting the code rate of a multimedia code stream. The device comprises a data communication interface module, a data packet dual-port buffer module, a calculation module and an output code rate control module, wherein the data communication interface module is used for receiving multiplexing frame data, and writing the multiplexing frame data into the data packet dual-port buffer module; the data packet dual-port buffer module is used for buffering the multiplexing frame data; the calculation module is used for calculating a packaged multiplexing code stream packet interval, and transmitting the packaged multiplexing code stream packet interval to the output code rate control module; the output code rate control module is used for transmitting the multiplexing frame data in the data packet dual-port buffer module by taking the packaged multiplexing code stream packet as a unit; and the packaged multiplexing code stream packet interval is a time interval for transmitting two adjacent packaged multiplexing code stream packets. The device and the method reduce the code rate when the multimedia code stream is transmitted so as to reduce errors such as packet loss or data packet synchronous loss and the like; and furthermore, an empty packet is not inserted when data is transmitted, so the device and the method avoid waste of transmission bandwidth.