Aiming at the field corn harvester harvesting seed corn is prone to the phenomenon of injury to ears and seeds, debris blockage, etc., a large-scale seed corn combine harvester for the biological characteristics of seed corn in the suitable harvest period was designed. The machine adopted small row spacing to row flexible plate picking cutting platform and replaceable combined peeling device, to ensure low-loss picking, conveying, peeling operation and reduce seed loss and damage, which was equipped with steel rubber-covered curved picking plate on the upper part of the cutting platform, “rubber+steel” clamping conveyor chain and six-pronged low-speed pulling rollers, and the replaceable combined peeling device adopted flexible peeling+rubbing+speed reduction. The main factors affecting the machine indexes were extracted by screening through the Plackett-Burman experimental design, and the Box-Behnken experimental design principle was applied, taking the forward speed of the machine, the rotational speed of the stem pulling roller and the rotational speed of the peeling roller as the experimental factors, and taking the total loss rate and the impurity rate as the experimental indexes, the machine was examined through the field test, and the best operating parameters of the machine were optimized. The test results showed that the total loss rate of cob was 1.61% and the impurity rate was 0.55% when the optimized machine forward speed was 4.87km/h, the stem pulling roller speed was 877.27r/min and the peeling roller speed was 442.52r/min. It was verified in the field test: when the forward speed of the harvester was 4.9km/h, the rotational speed of the stalk pulling roller was 880r/min, and the rotational speed of the peeling roller was 450r/min, the total loss rate of the cob was 1.64%, and the rate of impurity was 0.57%, which met the requirements of the mechanized joint harvesting of corn for seed production, and it can be used as a reference for the design and test of the joint harvesting machine for corn for seed production.