The invention belongs to the technical field of an agricultural machine, and especially relates to a mini-sized potato seeder seed-discharging amount adjusting device. An adjusting plate is subjectedto up and down movement along a guide groove by screwing a leading screw for adapting the mini-sized potato seeds with different sizes, and a purpose of adjusting a seed-discharging amount is realized; at the same time, an electric motor with cooperation of a shaft coupling and a connection shaft drives the connection shaft to rotate by surrounding axis of the connection shaft, a joint is fixed atan eccentric wheel of the connection shaft and winds the axis of the connection shaft, the eccentric wheel is connected with the adjusting plate through a bearing, a connection disc, and a connectingrod, under the effect of the eccentric wheel, the adjusting plate is subjected to up and down reciprocating motion with high frequency and low amplitude under constraint effect of the guide groove, and a purpose of junction preventing of a seed case seed-discharging port of the mini-sized potato species group is realized. The device has the advantages of simple structure, convenient operation, and strong adaptability, and realizes the purposes of adjusting the seed-discharging amount and preventing junction.