The harmonic drive is used in very high speed reduction or speed increase in a single stage. The flexspline of the harmonic drive should be made statically flexible to transmit motion but dynamically rigid to reduce vibration in high speed rotation. These two properties are coupled and cannot be satisfied with conventional materials. In this paper, the flexspline is manufactured with carbon fiber epoxy composite by elastomeric cascade tooling. The elastomeric cascade tooling is composed of a silicon rubber die and a conical steel core which increases the pressure of the silicon rubber die. The manufactured composite flexspline has better static and dynamic properties than those of steel flexspline. Also, the machining cost and time of the composite flexspline can be reduced compared to the steel flexspline.