Q: Hi I have a question my one friend knows my Apple ID and password and I m afraid he reads my all messages by signing in my Apple ID in his PC, is it possible..?

Sure it's possible.  Change your Apple ID password.

If he has your Apple iD and password he can sign in to Messages on his Apple device and receive your iMessages. Change your password. Change your Apple ID password - Apple Support

Yes, not only that, they can use your Apple ID to buy content.

Never share your Apple ID.

I suggest you change your password immediately:

https://appleid.apple.com

After that log/sign out your Apple ID everywhere that is used

Examples: Settings > iCloud, Settings > iTunes & App Store, etc....

then sign back in with the new password.