Hi Amiya,
I don't think there is any Eclipse plug-in for SAP PO.The below link do not have any SAP PO plug-in.
SAP Development Tools for Eclipse
You need to download NWDS for SAP PO related deveopement.You can read the below document for more details -
How To Use the ESR Eclipse Tool with the Enterp... | SCNhttp://www.sdn.sap.com/irj/scn/go/portal/prtroot/docs/library/uuid/60bf80bb-736f-2f10-4593-a57a6ccb0193?QuickLink=index&overridelayout=true&54417235668265
Thanks
Somil Gulati