Hi, how can i disable my bluetooth device, cos i didn't need it.

do you have an option in your bios to disable it?....check your mobo manual?

No. I am using dual boot. I don't want to use my bluetooth device in Linux. So, how can I disable it in linux?

If it's a USB stick, plug it out. If it's builtin (as in laptops that may have builtin bluetooth and/or wifi), there is usually a button to power and unpower it. For example in my laptop there are two buttons in the front: one for bluetooth, one for wireless radio. One click and the appropriate device is powered, another click and it's unpowered.

EDIT: some laptops have a Fn key, usually coloured blue and close to the Windows key if it exists, with which the user can control the laptop along with other "Fn -control keys": audio volume, screen brightness etc. And some laptops have a button for Bluetooth (with the Bluetooth "logo") that works like the power button I described above: Fn + Bt-button powers and unpowers the device.

Mine is using shortcut Fn+F2, i just can disable both wifi and bluetooth. but i just want to disable my bluetooth.

Another way that came to my mind is to remove the bluetooth device's module with rmmod (if it is a module and not built directly into the kernel). This should effectively bring the device down, and if you don't need the device (in your Linux operating system) at all and don't like the idea of loading it during boot and then unloading it by some script every time you start the thing, you can blacklist the module and have it done that way. Blacklisting means adding a line to the module blacklisting file (might depend on your distribution) that reads (without quotes) "blacklist modulename", where 'modulename' is the name of the module you want to blacklist - not to be loaded. I have used this only to prevet the bcm43xx module from being loaded for a wireless card when using ndiswrapper, but with fwcutter ndiswrapper is no more needed, and so I don't need to blacklist anything.

Try if you can't find any other solution. The Fn+somekey would probably be more ideal, as it allowed you to power the device again if you happened to need it.