Hi Lokesh,

Yes it is possible, it just depends a bit on how you do it.
You have two ways to do it:
1) Add the attachments manually from the chatter or from Settings > Technical > Database Structure > Attachments (requires developer mode to be activated) by creating a new record.
2) You can import the attachments through the import button under Settings > Technical > Database Structure > Attachments (requires developer mode to be activated). This means that all your attachments have to be converted into a base64 format so that you can import them in the datas field though. The base64 output should be in a column in your CSV/Excel file.

If both of those cases do not work or are not an option for you, you would need somebody technical to help. A developer can script the importing of attachments through XML-RPC to upload attachments in bulk into Odoo.

Regards,
Yenthe