This experiment was carried out in experiment field at Hoengseong from March to July 2015 to evaluate the seed productivity and feed value of oats (Avena sativa L.) according to the difference of seeding date. The experiment was arranged randomized complete design with three replications. The treatments were consisted of three seeding dates (12, 22 March and 2 April). The emergence and heading of oat showed a tendency to accelerate as the seeding date was delayed while the number of days taken for the flowering after the heading remained unchanged. The plant height, panicle length, number of culm, and number of panicle all tended to decrease with the delay of seeding date. The seed yield showed a significant difference with 3.55 ton/ha in 12 March and 2.38 ton/ha in 2 April (p<0.05). The dry matter yield also showed significantly different in 12 March and 2 April which were 6.57 ton/ha and 4.56 ton/ha, respectively (p<0.05). The feed value measured as CP (crude pretein), NDF (neutral detergent fiber), ADF (acid detergent fiber) and DMD (dry matter digestibility) showed no difference according to the seeding date. In the case of RFV (relative feed value), a decrease with the delay of seeding date was observed but only an insignificant difference (p>0.05). As the purpose of this study was not production of roughage but that of the seed, cultivation was in the full-ripe period, hence a relatively low feed value. In conclusion, it is considered that the appropriate seeding date for a spring cultivation of oats for the purpose of seed production in Hoengseong is in early March regarding growth characteristics, seed yield, and feed value.