When you install Android Studio, you’ll automatically get the latest version of the Android SDK. The SDK is constantly being updated with new features and security updates.

I cannot see Android SDK section in Android Studio preferences! This is the preferences which i see:
Can any one say how can i enable android SDK in preferences? It should be some thing like this:
Edit:Some cashed data causes this problem and even invalidate cashes not worked for this problem. So Uninstall android studio (with it's data) completely and install it again works successfully.
Android Sdk Download
1 Answer

I found the answer.Once I uninstalled the android studio and installed it again but it doesn't works. Then again I uninstalled the android studio and it cashes completely according to this post and installed it again. So it works and show Android SDK.