We studied the retina structure, differentiation, forming process and visual characteristics of Fourfinger Threadfin (Eleutheronema tetradactylum) in the early stage by paraffin serial sections, H.E staining and microscopic measurement. A total of 10 visual fields near retinal center of Fourfinger Threadfin at different developmental stages were randomly selected, and the total retinal thickness and the sub-layers retinal thickness of were measured with Qcapture Pro software and the average value was calculated. The numbers of nuclei in outer and inner nuclear layers, and the number of ganglion cells per unit length (100 μm) of each visual field were counted and the average value was calculated. At 8 h 54 min after fertilization, optic cup was formed but the retina of newly hatched larvae was not yet differentiated (Fig. 1a). Retinal pigment epithelium, outer nuclear layer, inner nuclear layer, ganglion cell layer at 2 days after hatching could be clearly defined (Fig. 1c). Horizontal cells, bipolar cells and amacrine cells in inner nuclear layer at 3 days after hatching had been differentiated (Fig. 1d). At 4 days after hatching, the retina structure was well developed (Fig. 1e). In after days 10 layers of retina could be clearly identified (Fig. 1f﹣i). The ratio of nuclei of photoreceptor layer to ganglion cells increased from 9 days to 14 days after hatching (Fig. 3), indicating that convergence degree of retina was elevated and this period was transitional period of visual characteristics. This was adapted to ecological shift of this species. In early stage, there were only one or two layers of horizontal cells and the sensitization system was underdeveloped. The visual acuity of larvae in the early stage was comparatively high and the vision played a very significant role in behavior and feeding and adapted to live in an adequate light environment. After they swam to shallow muddy bottoms, both the acuity and light sensitivity were weak, therefore, the vision did not have an important effect on behavior and feeding.