Can i use the old antenna on my house to get HD reception?

It depends.

Digital TV (DTV) uses the same RF bands as analog TV; VHF & UHF. If your old antenna picks up the band(s) the digital stations in your area are using, then you'll be fine. Most digital stations are on UHF, which covers stations from 14 to 69, at this time. If your old antenna is UHF and the digital stations in your area are UHF, then you'll be fine.

Try the local topic for your area, found in the topic listed below, to learn what band your local DTV stations are on:

http://www.avsforum.com/avs-vb/showthread.php?t=453241

It would also be helpful to know what band your antenna is. Here is a web site with pictures of various antennas, which one looks like yours?

http://www.starkelectronic.com/allant.htm

Can i use the old antenna on my house to get HD reception?

Easier answer: it's quite possible. Plug it in and find out.