The invention discloses a sampling nut used for a resistance-type moisture tester. The sampling nut comprises a support board, an outer drum and an inner screw drum. The outer drum and the inner screwdrum are integrally formed. The support board is connected with the outer drum and the inner screw drum in a welding manner. The support board is square. Four corners of the support board are equipped with first installing holes. On one side of the support board, a second installing hole is arranged between two first installing holes. The support board is installed in the interior of the resistance-type moisture tester by penetrating through the first installing holes and the second installing hole through screws. Screw threads are uniformly distributed in the inner screw drum. A screw grooveis formed between screw threads. The sampling nut is in clearance fit with screw threads below a sampling threaded rod. The clearance ranges from 0.1 to 0.35 mm. During operation, the sampling nut stably relates relative to the sampling threaded rod. Force is saved. Data acquired by sampling is stable, reliable and accurate.