The grey mullet, Mugil cephalus, goes down south area by the western coast side of Taiwan during every last ten days of November to the first ten days of January. It brings bumper harvest to the fishman in this period of time because of its high economic interest. The time of capturing and the amount of the grey mullet was changed and decreased gradually because the China fishman harvested the grey by the illegal bomb and the climate has changed. Therefore, the aquaculture of the grey mullet grew up. The grey to be culture is wild fry. The wild fry can be divided into four group by the capturing time. However it is difficult to distinguish the four types of the grey mullet by its appearance, especially the fry.The grey mullet can divided into four parts to sell, the eggs have economic worth most. If we can screen and select the female grey that can embrace great eggs, it will guarantee the feeding income. There are many factors to influence the maturation of the eggs, including growth factor, the physiological factor, the genetic factor and etc.. The aim of this research to find the microsatellite marker correlated to the genetic factor, it also can be a qualification standard to tell good from bed fry when selling and guying the fry.By the method of Dot blotting and southern hybridization, we get 48 colonies with microsatellite DNA sequence. We design 16 primers by Primer premier software, they are used to screen the difference of the ovary development among the grey mullet sample. The analysis result of this experiment accords with the concept of Takagi and Hizer, while analyzing other grey nullet samples in the future, if the size of 600-700 bp with Mce-1 locus,or to close to 500 bp size with Mce-10 locus, or 300 -400 bp and 600-700 bp size with Mce-12 locus, or 500-600 bp size with Mce-13 locus, they may represent and screen high GSI for grey mullet.