The invention discloses a self-sealed drainer of a pipe bundle drier, and belongs to the field of mechanical equipment. The drainer comprises a hollow half shaft placed in an end seal at the water outlet end; the circumference of the hollow half shaft is provided with a plurality of condensed water drain holes; an involute condensed water guide plate is led out of each condensed water drain hole along the external circle of the hollow half shaft; the involute condensed water guide plate is welded on the inner wall of the end seal; a drain groove is formed between the involute condensed water guide plate and the external circle of the hollow half shaft; and a cover plate is welded on the drain groove. According to the self-sealed drainer, the condensed water is in the drainer all the time in the whole rotation period of a pipe bundle so as to form water seal per se; the vapor does not pass through the drainer so that the vapor has no loss; and meanwhile, the condensed water does not form return flow in each drainer, so the drain amount of the condensed water is high, and the drying effect of materials is better.