The invention discloses a sampling piece for a resistance-type online moisture tester. The sampling piece comprises a sampling plate, wherein four corners of the sampling plate are all provided with circular grooves, the center point of the sampling plate serves as a dot, and snags are uniformly distributed around the periphery and the dot, ,; the sampling plate is made from a zinc alloy, the outer surface of the sampling piece is coated with a chromium layer, a lubrication layer and a waterproof layer in sequence; the sampling piece matches with a material spoon, the panel of one end of a sampling nut is in squeezed cooperation with the material spoon, the sampling nut is in threaded connection with a sampling threaded rod, a grain is placed in a sampling hole, the rotation, squeezing andfriction of the sampling threaded rod and snags on the sampling piece are used for grinding the grain so as to measure the moisture value in the grain, the arrangement of the tapered snags can enlarge the friction between the sampling threaded rod and the snags, so that the grain can be crushed easily, accurate data can be measured conveniently, the grain remaining on the sampling threaded rod and the snags can fall off easily, and the measurement of a next grain is not affected.