The utility model relates to an offal pipeline drain valve in building belongs to the drain line. The utility model provides a be orbed valve casing including the inner chamber, the connecting pipe isestablished to the both ends opening of valve casing, and inner cavity of the valve casing is equipped with half ball valve element, and half ball valve element's circular cross section indent is thespool chamber, and thickness is the same everywhere for half ball valve element's outer peripheral face and spool chamber medial surface, and half ball valve element establishes the pivot, and to runthrough the valve casing global and at valve casing peripheral hardware handle. The utility model has the advantages of: the utility model discloses be applied to on the drain line of the interior house offal pipeline of high -rise building, the utility model discloses can make residential customer open or close family internal drain pipe way at any time, avoid the upper strata to block up and lead to the cap problem of irritating of lower floor, the utility model discloses the structure is unique, and the filth of avoiding existing in the pipeline results in closing the valve inefficacy problem that the in -process probably appears.