The otoliths from 3789 individuals, taken monthly from the Chekiang coast, during the period from September 1958 to December 1959 inclusive, were used in the present investigation. Monthly observation on the marginal structure of the otoliths and terminal index of ,each ring group carried out over a period of one year confirmed that the rings on the otolith were formed annually (excluding the first ring of the autumn spawners), as there was an complete turning over of one sort margin to the other during a definite period of the year. It is therefore concluded that the otolith of the Large Yellow Croaker is a reliable index for age determination. The opaque zone at the margin began to appear in January. Its percentage occurrance was highest in May and June, and fell to zero in July. However, the period of commencement of formation of the opaque zone varied regularly according to the age of the fish. It began to appear in April in the individuals with 1-13 rings, in February and March in those with 14-17 rings, and as early as in January in those with 18 rings onward. A preliminary analysis of the monthly length frequency distribution of the young fish and of the marginal structure of the otoliths revealed that the first annual ring on the otoliths of the young fish of the spring spawners was formed one year after and that of the young fish of the autumn spawners a year and a half after being laid. During the winter and spring the growth of the otolith was very slow, but during the summer and autumn it showed remarkable growth. It can be deduced that the growth rate of the present species also varies periodically, i.e. it grows slowly in the earlier half of the year, and remarkably in the latter half of the year. In the present report, the distinction between the true annulus and the false annulus has also been described.