Dr Chi first said the hybrids may already exist in a lecture in 2012 but has now written a book on the subject.
His book, written in Korean, is called Alien Visitations and the End of Humanity.
He says he has identified four types of aliens – small, tall and bold, scaly with snake eyes, and insect-like.
Dr Chi believes the insect aliens may be in charge and give orders to the other types.
The aliens exist in their own bio-system that humans cannot experience because our perception is limited by our organs, the professor has claimed.
As the aliens are said to be highly intelligent, so Dr Chi believes they could solve the problems on Earth in the future, such as climate change.