Abstract: In order to recover from deforestation and find a sustainable way for the economic development in montane area,bird diversity and frugivorous birds were studied in forest succession fields at Mengsong area,Xishuangbanna,Yunnan Province.We identified the forest age for each type of fallow fields with local informati on.The sampling areas were established (5 ha.for each type) within the different habitats,and the surveys were conducted during the dry season and rainy season.We also observed and recorded species of frugivorous birds,which related seed dispersal in the forest succession fields.Birds were sampled by mist nets;they were ringed and released after getting their excrements.Many species of plant seeds were got from bird excrements.Our study shows that bird diversity increased with the increasing of forest stratification.There are similar varied regular on the value of the Shannon-Wiener Indexes (H,Hmax and J) for bird diversity in the dry season and rainy season.Diverse birds and their activity linked with the all fallow fields and the different patterns of forests.Birds sensi tively indicated the relationship between biodiversity and forest dynamic.The bird species with certain habitat have a special significance,especially the relationship between the forest dynamic and the frugivorous birds which related seed dispersal.Generally speaking,the study showed that we should pay more attention to the ecological principle of frugivorous birds and forest succession,and it was crucial to protect primary tropical forest and the birds in it.