The head of the black-headed swordsnake is large and clearly distinguished from the neck. The body is small, about 2/3 meters in length. The head and back are black, the back of the body is tan or dark brown, with a black ridge pattern, and the black ridge pattern of the young snake is clear; the ventral surface is yellow-white, and there is a black spot on both sides of each abdominal scale, and the front and rear are connected into two longitudinal lines.

Black-headed sword snake anterior scales 1, retro-orbital scales 2, temporal scales 2+2 , The anterior inferior temporal scale is larger, wedged between the seventh and eighth upper lip scales, and the upper lip scales are 3-3-8. The dorsal scales have 17 rows, smooth and without edges, the ventral scales are 171-187; the anal scales are divided into two; the lower caudal scales are 63-125 pairs.