Abstract: Carbon nanotubes (CNTs) with sharp tips were synthesized by a hydrogen arc discharge method. Three unusual morphologies, i.e., a cone-shaped tip, a suddenly-shrinking tip, and a pencil point-like tip were observed. These novel tip structures are considered to be related to the addition of a small amount of silicon powder in the raw material, which may introduce structural defects in the CNTs. The field emission property of the sharp-tip CNTs was investigated, and a low threshold electric field of 3.75V/m, a high field emission current density of ~1.6×10⁵A/cm², and a good emission stability were demonstrated. The superior field emission performance of the CNTs can be attributed to their good crystallinity and unique tip structures.