Based on cognitive principles, a general intelligent system model including consciousness system has been established, and two types of intelligent system methods-analytical system and holistic system, have been explained. Using mathematical methods, the composition that there must be at least one intelligent system, necessarily in the form of a basic unit knowledge network, which can only be a holistic system using the unique analytical method and approach to form the first knowledge about the world, based on the incompleteness of analytical methods and analytical intelligent systems, the wholeness and non-elementariness of the world and things, as well as the absence of existing holistic a priori knowledge that can be replicated in the world. To obtain such knowledge entirely on its own, a system must possess characteristics such as self-containment, self-sufficiency, and autonomy and can only be a conscious system with a basic unit knowledge network, its sequential activity mechanism, holistic activation mechanism, and external devices. Both cognitive and knowledge spaces formed within the consciousness system, together with the space of external objects and information, constitutes a closed and complete unified space. Any information processing is a self-mapping within the unified space. This is the fundamental principle of epistemological science, including cognition, consciousness, machine exploration, and other methodological sciences, totally known as the unified space principle. The issue of intelligence and consciousness is essentially an epistemological scientific problem.