Aiming at the difficulty in the preparation process of the optical inverted cone narrow tip, through a special design mask, the photoresist was subjected to two consecutive patterning processes by one stepping using a stepper. Breaking through the resolution limit of the UV lithography machine, an inverted cone structure pattern with a tip close to 50 nm was prepared.The photoresist was reflowed to solve the problem of layering, which ensures the smoothness of the sidewall of the structure and the integrity of the tip. In the deep silicon etching process, by adjusting the gas components in the etching, the surface morphology of the tapered structure is improved, and the uniformity and integrity of the structure are improved. Finally, an optical inverted cone with a tip close to 50 nm suitable for interlayer coupling is obtained.