It is very important to study the fast algorithm for the visibility of LEO satellites to improve the efficiency especially in event-driven and time-stepped real-time simulation environments.

A LEO constellation composed of two or more satellites can improve the time and space resolution and increase the number of occultation events greatly compared with a single LEO satellite.

Focused on the task of carrying out GPS occultation observations with a receiver set on LEO satellite, this paper developes the LEO orbit simulation system based on which the occultation events can be simulated taking into account the geometric relationship of the satellites and the field of view of the receiver antenna.

Focused on the mission of remote sensing geophysics parameters with GPS-reflection receiver set on LEO satellite,the reflection events are simulated taking into account the scan mode of satellite and receiver antenna parameters based on simplified general perturbation-4(SGP4) orbit prediction model.