Cement mortar plain bumper convenient to it is clean is including the examination mould position sleeve (1) of cement mortar plain bumper, its characterized in that examination mould position sleeve (1) go up and to have a mud capping board (2) of keeping off through a round pin axle movable mounting, keep off the thick liquid mouthful department of advancing that mud capping board (2) can make examination mould position sleeve (1) with the closing cap and open and be closed through opening. The utility model discloses the advantage is: the utility model has the advantages of simple and reasonable structure, change to equipment itself is less, can the regional cleanness of effectual reduction experiment measure, the cost is low, quality own is little, can not exert an influence to whole plain bumper weight.