The experiment was conducted to evaluate the effect of the different seeding date on the dry matter yield and chemical composition of oat for forage. The crops wrc sccdcd on August 3l(lirst). Scptember IO(second). and September 20(third seeding date) and were taken on November 24, 1991. The results are summarized as follows : 1. The plant heights were 68, 54 and 40 cm at first, second, and third seeding date, respetively. 2. Dry matter (DM) content decreased with delaying seeding date from first to third seeding date. DM varied from 18.6 to 14.9 %. 3. Leaf weight ratio increased with delaying seeding date from first to third seeding date, varied from 51 to 67 %, but stems decreased from 49 to 33 %. 4. The dry matter yields per ha decreased with delaying seeding date: it was 5.670. 3.960 and 2.310kg at first, second and third seeding date. Significant differences has been obtained among date(P<. 05). 5. The content of crude protein increased with delaying seeding date from first to third seeding date. varied from 16.3 to 22.6%. but NDF and ADF content decreased.