Tail of Yellow-bellied Prinia in winter is longer than in breeding season that may means a new survival and breeding strategy.So we studied autumn moulting of the adults of Yellow-bellied Prinia at Jiangxi village,Zhaoqing city,Guangdong from September 2006 to February 2007. The results showed that:(1)The length of the body and tail in breeding season was highly significant(P<0.01)shorter than non-breeding season,the length of wing was significant shorter(P<0.05),other body measurements had not significant difference between breeding and non-breeding season(P>0.05).(2)The specimen of Yellow-bellied Prinia got at 15th September showed that 5th primaries and 6th secondaries had been replaced,while the specimens collected after 20th November had finished the moult process.(3)The pattern of primaries replacement was descendant and Secondaries was ascendant,and tail feathers replaced as a centrifugal moulting pattern.(4)Body-mass varied during moulting periods and reached its maximum in October when the body mass was significantly heavier than November (P<0.01).However,no any significant difference in body mass was found between the remainder months (P>0.05).Hence,we supposed that:Autumn moulting of Yellow-bellied Prinia would take about 100 days and the tail replacement had more important effect than other feathers on the growth of Yellow-bellied Prinia.