The invention relates to a proximity sensing device and a radio frequency system, in particular to a proximity sensing device and a working band adjusting radio frequency system with self adaptability. The proximity sensing device is applied to a radio frequency device. The radio frequency device comprises an antenna module and a radio frequency circuit. The radio frequency circuit is electrically connected with the antenna module. The proximity sensing device comprises two direction coupling unit, a radio frequency power measuring unit, an analog digital conversion unit and a processing control unit. One direction coupling unit is electrically connected with the antenna module, the other direction coupling unit is electrically connected with the radio frequency circuit. The radio frequency power measuring unit is electrically connected with the direction coupling unit. The analog digital conversion unit is electrically connected with the radio frequency power measuring unit. The processing control unit is electrically connected with the analog digital conversion unit and the radio frequency circuit. The proximity sensing device and the radio frequency system can optimize the communication function and reduce damage of electromagnetic wave to a human body.