In the Bible it says [Gen 3:8]: "And they heard the sound of the Lord God walking in the garden in the cool of the day". It seems God has carnal body (thus he could walk). In Judaism compared with Christianity and Islam, they often think God is not in a visible form. So my question is 'is it real that God has a body in Judaism'?
The short answer to your question is "no", and that references to God's body in the biblical and rabbinic literature need to be understood figuratively. That said, there's a lot more to this than just "no", and there have been many religious Jews throughout history who have believed that God does (or at least can) possess corporeal form.
In his commentary on Tractate Sanhedrin in the Mishna, the Rambam (12th century) delineated thirteen principles that, at the time, he held to be crucial to Judaism. His third principle states that God does not possess a physical form. People tend to cite that principle today in asserting God's incorporeality.
Prof. Marc Shapiro wrote a book entitled The Limits of Orthodox Theology: Maimonides' Thirteen Principles Reappraised (Oxford, 2005), and in chapter 3 (45-70) he goes into some detail, listing the various rabbinic authorities throughout the ages who have either supported the view that God possesses physical form or who have disputed with the Rambam over his making it necessary to believe that God does not.
For an interesting example of an ancient text that discusses God's dimensions, and that the Rambam was influential in having destroyed, see Gershom Scholem's On the Mystical Shape of the Godhead (New York: Schocken Books, 1991) - in particular, pp15-37.
The earlier answer by Shimon bM addresses God's corporeality; I'll take another tack and address your reading of Genesis 3:8. You say it implies God's corporeality by saying He was walking through the garden; in fact, though, the plain reading IMO is that God's sound, not Himself, was walking (i.e., traveling, moving) through the garden, and this is the reading clearly favored by various commentators quoted by Nachmanides in his commentary.