In the fabrication of micronano optical fiber,the selection and control of fabrication methods and related parameters are important factors that affect the optical transmission characteristics. Based on the single mode optical fiber, the related parameters and transmission optical properties during the preparation of micronano fiber (MNF) by using the fused biconical tapering and hydrofluoric acid (HF) corrosion method are simulated theoretically and analyzed experimentally in this paper.The research shows that in the process of MNF,when the diameter is reduced from 20 μm to 0,the transmission power loss is up to 97%.Due to the influence of coupling loss and environmental refractive index changes, although there is a certain difference between the theoretical loss value and the experimental results, the change law remains the same.Through OptiFDTD software simulation,it is pointed out that the depth of the evanescent field increases with the decrease of the fiber diameter,and there is a nonlinear relationship with the loss.When the wavelength of the input light wave is compared with the diameter of the fiber,the energy is almost entirely concentrated on the surface of the fiber,and the sensitivity of the external environment change to the optical waveguide response in the fiber is increased.This characteristic of micronano optical fiber has potential application in the field of sensor.