Any kind of logic should face a world, formal logic is no exception. It mainly faces the world of things, which is the existence basis of formal logic. The world of things is a kind of theoretical world; it has "legitimacy", and accords with the natural disposition of human being, namely the eager for certainty. Formal logic is the logic support of the world of things, the development level and style of formal logic restricts the specific form of the world of things. The theoretical development possesses inherent consistency with formal logic. The world of things is an inevitable world, a natural world, and a world of knowledge. As a logic facing the world of things, formal logic fit with the world of things in the nature, and it has inevitability, controllability, and computability, etc.