List one technique, if you know, to change people's behavior.

Why do you want to change anyone's behavior? Firstly its that person's own decision and secondly, we never know what we think is "better" might not actually be better. There could always be a higher plan of things and perhaps the current behaviour is something that is important for them to realize some life-changing things. Secondly, changing others most often has unintended side-effects.

Quite a few problems are solved when we change our own "view" about others. Sometimes if we really accept them as they are (they might be wrong too), but we start noticing the positives and realize many things which we never did before. Heck it also may happen that those positives make you think that the person has changed.

However since I still haven't answered your question, heres what I have experienced myself:
"Be the change you want to see in the world" - Gandhi
My personal experience is, well the world is a big thing, but your closer surroundings start to change when you act out the change yourself.

There are some intervention techniques in organizational development, most of which are based on Kurt Lewin's model of change management - unfreeze, relocate, and re-freeze.
The first thing that you must encounter is the people's resistance to change. Address their legitimate concerns and explain to them the benefits of adopting change. This shall help you take them on board.
Next, train the participants and make sure that you are achieving the objectives of the training. This may require implementing parts of the new system that you wish to introduce into your organization.
Finally, your new system can “go live” with you continually following-up to ensure that the newly implemented system can integrate with the organization and help people succeed.

About me: Worked for 2 years as a consultant in areas of recruitment, corporate training and organizational development.

Note: I didn't read your comment on the above answer before nor did u describe what exactly you're asking for in your question but since I have written a detailed answer that can help anyone else so I'm not editing it.

I think you need to elaborate your questions, I assume by people's behavior you mean negative behavior? if so it is then yeah at times we need to improve it, I'm using the word "improve" here because I dun believe to change people actually, It's not a technique but it's a way that "the people don't change, environment does"
that includes your own self, the place you live in, the people you live with etc. For example, the kids who have grumpiness in their attitudes, have actually brought up with the people who have aggressive n grumpy behavior. It's like an reaction of an action, If action was positive, the reaction is gonna be positive too.

Well there is a technique I know but I haven't tried it yet, I have studied about colors, they have some psychological affects on human nature. for example the color red makes you aggressive and emotional as it's a warm color and the green and blue colors would make you fell coolers, as they are the colors of nature.
http://www.arttherapyblog.com/online/color-psychology-psychologica-effects-of-colors/

I will suggest a very commonly used technique. Firstly, communicate the change you want to see properly and clearly in your organization. The top management should be practicing it to set example in front of their employees. Except for that provide positive and negative rewards on expected and unexpected behavior of employees. Also provide extrinsic incentive to them because motivation is very important. Keep evaluating their behavior like by using 360 degree and remind them constantly until that change gets a part of your management

Be nice to others. Be a good person. When they see you as a good person, they will get attracted to you and could change their behavior to a good one. :)

i think changing her/his behaviour would be possible if you try to make him/her realize their faults and give logically arguments so that he/she would think on it and try to change his/her behaviour ...!

i have more proven techniques but ill give you the simple one.. change your behaviour...