The purpose of this study was to investigate the developmental dynamic changes in histological structure of diencephalic oculomotor nucleus in Leiothrix lutea nestling at different days of age. The microstructure of diencephalic oculomotor nucleus at one, five and nine days after hatching were observed and a special staining method-toluidine blue staining (TBS) was employed. The significance among different ages was analyzed by one-way analysis of variance analysis, and results were presented as mean ± standard deviation (Mean ± SD). The analysis was conducted using SPSS 16.0 for windows. The results suggested that there were four parts of nuclei, namely nucleus nervioculomotorii pars dorsolateralis (OMdl), nucleus nervi oculomotorri pars dorsomedialis (OMdm), nucleus nervioculomotorii pars ventralis (OMv) and nucleus of edinger-westphal (EW) (as shown in Table 1 and Fig. 1). Oculomotor nucleus of L. lutea nestling was comprised of small and large types of nerve cells, but the population, proportion and distribution of the two types of cells in different sub-regions were different as the days go by, and intracytoplasmic nissl bodies increased gradually with growth. There was no significant change in the relative position between different cerebellar nuclei, but both the interval and sectional area were increased from the age of 1 to 9 days (Fig. 2, 3 and 4). The results show that the structure of oculomotor nucleus matures with the growth of the L. lutea nestling, which is in accordance with its gradually improved neuroregulation of eye muscles.