I want to become a ceo of multi national company how I study so achieve my goal currently I am studying in 12 and i am going to btech ?

In your graduation try to participate in a lot of stuff related to management and case studies, be it college fest it will create a good impact on your CV.  If you have some good network then try to grab internship for Management at this company even You can do research Intern in management institutes like IIMs during your B Tech but keep in mind you should target one particular Topic to grab such kind of Intern. Work for E Cell of your college, if someone is planning for startup join them and learn how a startup works, build contact with the management of different funding ventures. If you have any good idea for a startup then show them at different competitions and get funding and become CEO of that startup. Later grow that startup and sell it to a big company. Now you have good CV with good experience.

Now try to get into Harward for Post graduation in management once you complete it, You will easily grab a good position at management in big MNC, now work hard for that company and make significant contributions to that company, you will be promoted If you are lucky enough you will be promoted to CEO one day and that way you can achieve your dream.

This is only one way but not the only way, You can be a CEO without having a degree from college it all depend upon how to improve yourself and identify a leader out of You.