Thank you for helping me to figure it out this. I have two sites: The Chinese site is using the main domain as www The English site is using the sub domain as en The Chinese site was built first and keywords well ranked in google. But now, I believe the English site will have more potential. so I wanna use the main domain for the English site, and use sub-domain cn for the Chinese site. I know if I do so. I may lose all the ranking in google. Any ideas to avoid or minimize the loss?