Among vast stars in the universe, the earth is distinctive for the existence of intelligent life on its surface. We wonder the origin of life, and meanwhile, we are also intrigued by the emergence of intelligence. What is the essence of intelligence? How does it emerge? During the Cambrian Explosion, a huge amount of species burst, moreover, the nervous system emerged for information perception, coding and processing. Contemporaneously, insects emerged and have existed for 400 million years in the complicated and fickle environment. In this article, we discuss the basic properties of intelligence on the basis of research findings in modern Drosophila cognitive neuroscience. We thereby propose that Drosophila brain is an important milestone in the emergence of intelligence, thus serving as the first station in our journey of uncovering the intelligence essence and entering the kingdom of intelligence.