The invention relates to an internal mold for a cold-drawing steel tube with small caliber. The whole shape of the internal mold is columnar; a connecting part is tapered; the internal mold also comprises a transition region, a wall reducing region and a wall fixing region sequentially; the wall reducing region is positioned between the transition region and the wall fixing region; the diameter ofthe wall reducing region is gradually reduced; and the outer wall of the wall reducing region forms an annular bevel. The internal mold is characterized in that an included angle between the annularbevel of the wall reducing region and a horizontal ring surface of the outer wall of the wall fixing region is between 28 and 32 degrees; the axle wires of the wall fixing region, the wall reducing region and the transition region are provided with an axial pylome; and the outlets of the axial pylome are arranged on the end face of the wall fixing region and a bevel of an interface between the connecting part and the periphery of the transition region respectively. After the included angle is increased, the internal mold farthest increases the wall reducing amount and diameter reducing amount,thereby reducing workload and production cost. After the axial pylome is added, the radiating effect of the internal mold is improved; the cold-drawing steel tube is uneasy to generate deviation of dimensional tolerance of an inner hole by thermal expansion and cold contraction; moreover, the arrangement of the pylome also lays a foundation for the implementation of a cooling process.