The variation of morphology about the glochidia of Hyriopsis curningii which went into the water parasitized in the gill of fish(yellow catfish) falled off the host fish was observed through optical microscope and scanning electron microscope.The results showed: the growth rate of the length and height of the shell and length of the intertwisting part were different.Under the scanning electron microscope,the glochidia of Hyriopsis cumingii had hook in the belly during the water,but the hook disappeared in the host fish.The glochidia had a little ridge and two thin wing which linked with the edge of belly,thick and little thornies were distributed over the ridge and wings.The silk of the feet of the glochidia disappeared and the interior apparatus formed gradually.