Abstract: A method for reducing frequency interference, and a communication satellite system. The method includes configuring the communication satellite system, determining a first range of areas in which a spatial isolation angle between the LEO satellite and the GEO satellite does not satisfy a minimum spatial isolation angle within service areas of the movable spot beams, enabling the movable spot beams to not enter the areas, and when the movable spot beams of the transmitting and receiving user antennas of multiple adjacent LEO satellites provide services to a same area, calculating a spatial isolation angles between the movable spot beams of the transmitting and receiving user antennas of any two adjacent LEO satellites, and in response to the spatial isolation angle not satisfying the minimum spatial isolation angle, assigning different sub-frequencies to the movable spot beams that do not satisfy the minimum spatial isolation angle.