The invention discloses a sealing component for a separation membrane piece. The sealing component comprises the separation membrane piece and a mounting part which can be fixed with a matching part in an airtight manner, wherein a passage penetrating through the two ends of the separation membrane piece is formed in the separation membrane piece; the mounting part is arranged on the separation membrane piece; the outer contour of the mounting part is larger than that of the separation membrane piece. According to the sealing component, a sealing ring with a deterministic geometric shape and dimension is directly formed on the separation membrane piece, so that the requirement on the geometric dimension accuracy of the membrane piece is lowered, the production cost and mechanical finishing cost of the membrane piece are reduced, a large batch of separation membrane pieces can be conveniently assembled on a liquid collector (tank) as long as the differences of the separation membrane pieces in shape (flatness), dimension and the like do not exceed the geometric shape and dimension tolerance range of the mounting part, and reliable sealing performance is achieved.