Optical fiber transmission is widely used, so the optical transmission characteristics of utmost importance. Many types of optical transmission, and here I step on the weak-guided wave fiber wave equation to study and understand the step-index optical waveguide mode, are second-order differential equations Bessel equation. Normalized frequency V depends on fiber-optical wavelength and parameters, it can be identified in the conduction mode optical fiber number. The introduction of critical theory fluctuations optical theory, simulation tools - MATLAB software, optical fiber transmission of the structure and principles. Step focus on analysis and description of the fiber-optic transmission characteristics. MTLAB step to map out the use of optical fiber LP01 low-end models in the section on the distribution of strength.