Abstract: The medium-orbit Earth satellite would travel through the slot region of the Earth's radiation belt, where the charged particle environment may fluctuate significantly, adding uncertainty of input for the anti-radiation design. Based on the typical models of the Earth radiation belts, the main sources causing the cumulative radiations for medium-orbit satellites are analyzed. Along with the dynamic variation characteristics of the particle radiation environment in the slot region, the influences on the radiation effects on the medium- orbit satellites are preliminarily estimated. It is shown that the dynamics of the slot region has little additional effect on the radiation damages of the surface materials and the solar cells. The proton filling events in the slot region have a significant effect on the total ionization dose in orbits above 8000 km (but the probability of such events is very low). The electron filling event in the slot region has a significant additive effect on the total ionization dose in orbits above 10 000 km, which must be taken into account in the corresponding radiation hardening design.