Hello Sudhanshu Mishra,
Thank you for using Apple Support Communities!
You can have iTunes reference the content where ever it is on your HDD without copying the content to the iTunes library, thus using twice the space.
If iTunes is set to "Copy files to the iTunes Music folder when adding to library," iTunes will copy all content that is added to the iTunes library to the iTunes Music folder. To adjust this setting or change the location of this folder, go to the Advanced tab in iTunes Preferences.
From: Adding music and other content to iTunes
Additionally if you want the content to then ALSO be located in your iTunes Library folder so everything is all kept together nice and tidy, use this:
Depending on how you imported items into iTunes, some items in your library might be stored in different locations (in another folder or on another hard disk, for example).
You can consolidate all the files in your library in the iTunes folder—for example, to make it easier to move your library to a new computer.
- Choose File > Library > Organize Library.
- Select “Consolidate files.”Files remain in their original locations, and copies are placed in the iTunes folder.
- To create folders (Music, Movies, TV Shows, Podcasts, Audiobooks, and so on) inside your iTunes folder, and place all your imported media files in the appropriate folders, select “Reorganize files in the folder ‘iTunes Media.’”
From: help://bookmark='https://help.apple.com/itunes/mac/11.0/help/index.html?localePath=English.lproj# itns2999'