Abstract: In the process of electromagnetic wave transmission from the cosmic space to the earth, it is inevitable that it needs to pass through the earth’s ionosphere and be affected by the ionosphere refraction, reflection, penetration and so on. In order to study the propagation path of electromagnetic waves in the ionosphere, this paper utilizes the data of IRI2016 ionosphere model and NRLMSISE-00 model, based on the ray tracing algorithm, and comprehensively utilizes the Runge-Kutta method and the variable step size to realize the electromagnetic wave propagation path in the ionosphere.The Runge-Kutta method is used, and a variable step size is adopted to realize the transmission calculation of electromagnetic waves in the ionosphere multilayer space complex plasma. Meanwhile, this paper also studies the propagation paths of electromagnetic waves of different frequencies and latitudes in the ionosphere. The study shows that: higher frequency electromagnetic waves are less disturbed by the ionosphere, and the offset angle of electromagnetic propagation is only 0.795° at 100MHz; the non-uniform layered structure of the ionosphere determines the multi-mode phenomenon of electromagnetic wave transmission, and is affected by illumination, and is strongly disturbed by the ionosphere during daytime and mid-latitude, and the offset angle is greater than 2.2°, compared with the nighttime and low and high latitude. The offset is larger than 2.2°, compared to the nighttime and low and high latitude regions.