Abstract: The micro-ecological factors and the biological reaction of the stocks in a fourteen-year-oldseed orchard were observed in the thinned and unthinned areas over two years after intensive thinning(about 40% ～50% trees were removed).The results were shown that the micro-ecological environmental factors in the thinned areas were much improved,such as relative low humidity,high windspeed during pollen dispersal Period,Especially the intensity of sunshine is about 10 times highter inthe thinned areas than that in the unthinned areas.The relative amount of pollen dispersal is 1. 4 timeshigher in the thinned areas.The female, male flowers and new shoots on the crown were 3, 2. 14 and8 times increased respectively.The seed outputs had reached to 30～45 kg/hm~2 in the fourth year after being thinned.It is concluded that conducting intensive thinning will be helpful to the promotion offlower-bearing and corn-bearing in some adult seed orchard.