The facial dangerous triangle usually refers to the triangular area formed by the line connecting the corners of the mouth on both sides to the root of the nose. In layman's terms, it is from the root of the nose to the corners of the mouth. This area is recognized as a dangerous area. When inflammation occurs on the face, especially when there is infection in this triangular area, thrombosis is likely to form in the veins in front of the face, affecting normal venous blood return, and backflow to The superior ophthalmic vein leads to the cavernous sinus on both sides of the sella turcica in the skull through the supraorbital cavity, spreading facial inflammation into the skull, causing serious complications of cavernous sinus suppuration and thrombophlebitis.