A parabolic conformal multi-order OAM-generating transmitarray with novel C-I-shaped gating cell is presented in this paper. The novel cell is composed of three layers of the upper and lower grating structures, and the C-I-shaped metal in the middle layer. Compared with the traditional C-shaped structure, the novel cell can be adjusted to cover 360° transmission phase change with high transmission coefficient at the frequency band of 10-20 GHz. To approximate the parabolic conformal shape, the transmittarray is designed and constructed by using the eight fan-shaped sectors with the one isosceles triangle and three isosceles trapezoid planar subarrays. Finally, the 1-th and 2-th order-mode OAM-generating transmitarrays are fabricated and measured, and the measured results basically agree with the simulated ones, verifying the parabolic conformal design method. The proposed parabolic conformal scheme will rich conformal transmitarray design method for adapting to the future complex communication and detection environments.