Based on the data provided by the International GNSS Service Organization (IGS), this paper systematically explores the core theory and realization method of GPS satellite observation data simulation. By accurately constructing the GPS satellite trajectory model and combining with the simulation of a series of error sources such as satellite clock difference, ionospheric delay, tropospheric delay, this paper realizes the simulation calculation of airborne GPS observation data. In order to verify the validity of the simulation model, this paper compares and analyzes the pseudorange observation data obtained from the simulation with the results of the precision ephemeris calculation, and evaluates the accuracy and reliability of the model in depth. The comparison results show that although the simulated data can better reflect the characteristics of the satellite trajectory under the actual observation conditions, in some cases, the results of the precision ephemeris are more accurate due to its higher time resolution and precision.