Disclosed is a codec (coder/decoder) system with shadow buffers and method of performing a Power Down/Suspend mode operation on this codec system, which allows all the codecs in the codec system to know the operating status of each other so that system crash can be prevented during a power down/suspend operation. The codec system includes two or more codecs and associated codec controllers, with each codec controller including a status data buffer and a shadow buffer; and each codec controller utilizes the status data buffer therein for registering the operating status thereof and meanwhile utilizes the shadow buffer therein for storing a copy of the operating status data stored in the status data buffer of the other codec controller. The provision of the shallow buffers allows all the codecs in the codec system to be capable of knowing the operating status of each other. This feature can help prevent system crash during power down/suspend operation.