Аннотация:n this paper problem mathematic modeling of radar system to measure inter-satellite parameters spaceship to space station is discussed. Modern space stations like International Space Station have big area of outer surface and then electromagnetic waves emitted by antenna are reflected from this surface and make interference with direct waves. This leads to errors in parameter measurement and fault of system of automatic rendezvous and docking. Author presents new algorithm to find reflected electromagnetic wave using physical optics approximation and ray tracing approach. Presented mathematic modeling algorithm is used in new approach to analyze trajectory of rendezvous spaceship to space station to find segments where radar system can work in wrong way. Described algorithms are implemented in modeling software, which was used for analysis of approaching and docking trajectories cargo and transport spaceships to International Space Station. The results of modeling are compared with telemetric information received from spaceships and International Space Station.