The utility model relates to a filter unit at a pump inlet of a nuclear power plant. The filter unit comprises a connecting pipeline, a filter screen and a pollution discharge pipeline, wherein the connecting pipeline is detachably connected inside a pending filtration system, and the pollution discharge pipeline is used for discharging impurities in the filter screen; the filter screen comprises a water inlet end, a water outlet end and a filtration part for connecting the water inlet end and the water outlet end; the filter screen is arranged inside the connecting pipeline; the water inlet end is detachably connected to the connecting pipeline, and the water outlet end is detachably connected to the pollution discharge pipeline; a first valve is aslo arranged inside the filter screen.