Abstract: Using equal design method,a field experiment was carried out at Wuqiao field station of China Agricultural University in Hebei Province to study the effects of different accumulated temperature before winter and planting density on tillering dynamics of forage rye (Secale cereale L.).The results showed that the tiller number per plant was affected by sowing date and seed density.In the prophase of forage rye,the tiller number per plant was mainly influenced by sowing date;while in the anaphase,it was mainly determined by seed density. Generally,earlier and fewer sowing norm could raise the tiller number in individual plant.In the prophase,metaphase,or anaphase of forage rye,the tiller number per unit area decreased with the postponing of sowing date,and increased with the increase of sowing norm.The sowing date and sowing norm had decisive effect on the number of effective stem per unit area.Suitable population structure was dependent on the increase of effective stem number per plant under the conditions of earlier sowing,and of effective stem number per unit area under the conditions of later sowing.