Trying to install Xcode on Yosemite 10.10.5

I'm trying to install Xode 7 beta 6 version on Yosemite. I used the command 'Xcode-select --install' in terminal. It says 'xcode-select: error: command line tools are already installed, use "Software Update" to install updates.' But i'm using latest version of OS X. What should i do? Please help me...

You are trying to install Xcode 7 on OS X 10.10. There's your problem. If you read the developer website, it would tell you it can only be installed on OS X 10.11. No exceptions. My advice would be to either: a) use a new computer to test Xcode 7 and El Capitan, b) Use a new partition for that, or c) Wait for the official releases within a month or so.

Xcode 7.2.1 should install correctly. This version of Xcode is currently working on my MacBook Pro running OS X 10.10.5 Yosemite.