An MP3 application device is provided. The MP3 application device comprises a host interface module, a playing module and a loudspeaker or a frequency modulation transmitter. Furthermore, a universal serial bus (USB) device or a memory card can be plugged into the MP3 application device. In this invention, the playing module issues a fetch instruction to read MP3 code data from the USB device or the memory card. An MP3 decoder with the playing module decodes the MP3 code data into voice data. The voice data is transmitted to the loudspeaker and broadcast. Alternatively, the voice data is sent to the frequency modulation transmitter and transmitted as wireless signals.