I think that Android emulator works like a Virtual Box, and uses the properties of the Host machine( Like virtual network interface), then why it can not use the Host Bluetooth.
You can't. The emulator does not support Bluetooth, as mentioned in the SDK's docs and several other places. Android emulator does not have bluetooth capabilities".
You can only use real devices.
Emulator Limitations
The functional limitations of the emulator include:
No support for placing or receiving actual phone calls. However, You can simulate phone calls (placed and received) through the emulator console
No support for USB
No support for device-attached headphones
No support for determining SD card insert/eject
No support for WiFi, Bluetooth, NFC