Good(ness): things, including behavior, that you like or prefer, or at least where you like or prefer what you take to be the ultimate consequence or upshot of the thing in question.

Perfection: when you have an ideal for something and that ideal is met, or when you feel that something couldn't possibly be better than it is.

The relation is that perfection is the pinnacle of good(ness).

I don't agree with Plato's views (and my comments above have nothing to do with Plato if you're asking for homework purposes), but you can find some info about Plato's idea of "the good" and perfection here:
https://plato.stanford.edu/entries/perfect-goodness/
and more simply here:
https://en.wikipedia.org/wiki/Form_of_the_Good

If the theory of Plato is wrong, why does it influence so much in Western Philosophy?
Is there any relation between goodness and the moral behavior or ethic?

If the theory of Plato is wrong, why does it influence so much in Western Philosophy? — nguyen dung

Whether one thinks that Plato was right or wrong about goodness or government or anything else isn't the same as whether or not Plato was influential. Plato was very influential, and his views were substantive, meaning they were weighty and not easily dismissed.

the Bible and Buddha are also highly influential; either might not be right or wrong about a good many things.

Why does the Supreme Form of Bad not exist?

In Christian theology the supreme form of bad is personified in the figure of Satan. In the mythology, Satan, also called Lucifer the light bearer, rebelled against God. He apparently felt his talents were not adequately appreciated. He was expelled from heaven and sent to hell with his followers. Satan is considered the ultimate 'bad' because he rebelled against God, the ultimate 'good'.

Maybe part of the problem of identifying "the ultimate bad" is that people keep raising the standard for how bad something can be. At one time, the Armenian genocide by the Turks was the ultimate bad. Then Hitler came along and was much worse than the Turks. At one time Pol Pot was considered the worst. Then the Rwandan Hutus wiped out many Tutsis with machetes. And so on.

World War I was really very very bad. But World War II was worse. World War III will be the ultimate bad. Until World War IV.

What is "good" is like pure gold. It can't get any purer than pure. Good is good. A pile of garbage might stink, but then the next pile of garbage will smell much worse, and so on. "Bad" is more subject to degrees of intensification than "good" is subject to degrees of good.

Maybe. What do you think.

In Christian theology the supreme form of bad is personified in the figure of Satan. — Bitter Crank

I think the right understanding of the nature of evil is that it comprises the 'privation of the good'. In other words, evil does not actually exist - or rather, it exists in the same way that shadows exist, or illness exists. Shadows only exist because there is light in the first place, so their reality is only derivative of light, in the sense of their being the absence of light. Likewise, illness (dis-ease) is simply the absence or privation of health (or 'ease'), and only exists relative to health; there can be no 'pure illness' but there can be 'good health'.

So following Plato( maybe in Philosophy in general?) all real things are good.?

Where did you get that?

I know that Supreme Form must be Real and Perfect,but I do not understand why it must be Good .Follow Plato the Supreme Form must be Real and supreme Perfect therefore must be supreme Good.What make Plato thinks that if he not consider the Reality means Goodness?

If we define God is Supreme Form of Goodness and Evil is Supreme Form of Badness.Then how can we deduce that God creates (causes) all things