Abstract: The plant number and yield of forage growing in different time were observed and recorded in successive three years.The results showed that temperate specise(Trifolium repens cv.Haifa and Dactyls glomerate cv.Porto)sowed grew poor in the spring and that sowed m the autumn grew well.On the contrary,tropical species (Macroptilium atropurpureum cv.Siratro and Digitarta smutsii cv.Premier Finger grass)grew well sowed in the spring and that soved in the autumn grew poor.The method of grey cot relation analysis was applied by using the synthetic evaluation indexes such as plants number.colour.relative forage yield.height,width,flowering,relative seeds yield,lodging months and actual yield as sub-sequence,and ideal values as the sequence.The result was suitable for the changing of plant number and yield.