This paper is an attempt to provide a brief review of background and an introduction to those complex systems and the chaos complexity theory in second language acquisition. It is divided into three sections: First, a short developmental background of the notion of chaos complex systems, chaos complexity theory and how it works is provided; then a comparison has been made between its similarities and differences with language learning environment; and finally, it is been related to the notion of second language acquisition. The twentieth century faced with an explosion of scientific and technological progression in human history; aligned with communication and information growth than before through evolution of computer science and technology. At the same time, this evolution has its impact on others sciences such as language learning, theories and approaches of language acquisition, facilitative tools and materials in language learning have been varied and upgraded. And at the same time, new questions have been formed which needed to be answered, questions such as; Does the brain operate more like a computer, storing and processing information? Do learners have language acquisition device (LAD)? Do learners require i+1 level of input in order to learn, or are they aware of noticing hypothesis?
