The fine structure of zoaea compound eye of Eriocheir sinensis was studied by electron microscope. The results showed that the shape of the compound eye changed with developing of the larvae from zoaea I to zoaea V. The surface area of the compound eye increased from 15400μm2 in zoaea I to 0. 4mm 2 in zoaea V. The shape of an ommatidium like a bubble in zoaea I changed into a hexagon in zoaea II. The dioptre part of an ommatidium , including corea , corneagenous cell and cone cell , under goes a development and a mature in zoaea stage. Theeightretinularcells,whichcomposedthesensatepartofanommatidium,weredividedintodistalpart (one cell) and proximal part (seven cells) . The diameter of the rhabdom increased from 3. 6μmto 5.3μm with the development of the zoaea to fellow a multiplying of quantity of the microvillus. A large number of Golgi bodies are a feature of the structure of a retinular cell in zoaea. The number and the kind of the organelles in the cell increase with the developing of the zoaea. In zoaea V an ommatidium has a structure similar to adult in light adaptation. The fine structure indicates that zoaea larvae obtains the function of the light sensation gradually.