Litter box liner

A litter box liner includes a plurality of removable layers stacked one inside of the other and conformable to the shape of the interior surface of a litter box. The liner includes an imperforate bottom layer and a plurality of screening layers positioned above the bottom layer. Each screening layer includes a bottom wall with a plurality of openings therethrough which are large enough to pass granular litter but small enough to block animal excrement. The screening layer also includes an imperforate flap attached beneath the bottom wall by a flexible edge connector, with the flap being large enough to cover all of the openings. The animal excrement may be screened from the litter by pulling upward on the uppermost layer and allowing the litter to pass through the openings as the flap drops down.