Abstract: ‘Yulu Xiangli’pear has wizened bud phenomenon in some orchards，which induces low yield. Experiments were conducted to investigate the appearing time and relative reasons induced wizened bud including endogenous hormone contents，carbon and nitrogen nutrition during flower bud differentiation using normal flower buds in short shoot from Weixian，Hebei and Taigu，Shanxi as control，wizened bud in Weixian as research material with methods of paraffin method，indirect ELISA，anthrone colorimetry and Kjeldahl in order to explore the formation mechanism then provide the theory for the prevention of wizened bud in pear. The results showed that wizened bud phenomenon appeared during sepal differentiation phase from early July to mid July. The content of indole acetic acid（IAA）in wizened bud was obviously higher than normal during initial period. The content of abscisic acid（ABA）in the wizened bud was significantly lower than normal during mid June to mid August. But the content of gibberellic acid（GA3）was significantly higher in wizened bud than normal. Content of the zeatin riboside（ZR）in wizened bud was significantly higher than that in the normal pear orchard from early June to mid June. ZR/GA3，ABA/GA3，and ABA/ZR in buds of normal pear orchard were significantly higher than those in the wizened bud pear orchard. The annual branch growth amount in the wizened bud pear orchard were significantly more than normal pear orchards. Days of annual branches growth in the wizened bud pear orchard were significantly longer than normal pear orchards. Soluble sugar，starch and C/N in wizened bud were significantly lower than those in the normal buds. In wizened bud pear orchard，the branches grow faster and buds had high content of IAA，GA3 and low content of ABA，carbohydrate，which inhibited the normal differentiation of flower buds and induced the occurrence of wizened bud.

Key words: pear, flower bud differentiation, wizened bud, endogenous hormone, carbon and nitrogen nutrition