Based on the nearly-ballistic optimization method, a high performance uni-traveling-carrier photodiode (UTC-PD) design scheme is proposed in this paper. The UTC-PD prepared by this scheme has high response speed, high responsivity, and large saturation output, and can alleviate the load voltage swing effect. The designed novel photodiode uses a partially depleted absorption layer with gradient doping. A thin p-type doped charge layer is inserted at the bottom of the collection layer. The internal electric field of the device is optimized to make the photogenerated electrons drift at the overshoot speed, reduce the electron transit time, make the device have high bias voltage operation ability, and therefore increase the 3 dB bandwidth and improve the saturation performance. Simulation results show that under the condition of high reverse bias voltage of 8 V, the device with an active area of 16 μm 2 can obtain a 3 dB bandwidth exceeding 86 GHz with a responsivity of 0.17 A/W.