SmartBell combines the technology of wireless remote control door bell and human body induction, more flexible, a good advantage over ordinary doorbell. It is available to replace doorbell audio through micro SD card and have another function of human body induction. It is placed near the door. When people enter the induction range, SmartBell can accurately identify, detect and have passive sensing of human activities, then play voice. Like cat's eyes, it is not depending on the light, can work stably and reliably in the dark environment, overcoming the shortcomings of light induction. Human body induction function can also be shielded, retaining only the wireless doorbell function