Hi Amit & Abhishek,
The Password will be as highlighted below depending on Individual / Non-Individual...
"To extract the zip file / to open PDF file, please enter the date of birth in case of individual tax payers and the date of incorporation for non-individual tax payers as password in the format of DDMMYYYY (Date of Birth/ Date of Incorporation should be same as printed on PAN card). For example, if your date of birth / incorporation is November 23, 1985 then the password will be 23111985.
For extraction of files use WinZip version 9.0 and above, WinRaR version 3.90 and above and 7-Zip version 4.65 and above.
To open PDF file use Adobe Reader version 5.0 and above."
This Information is also given just below the download option.