The number, histological characteristics, types and distribution of mucus cells in the pyloric caecum of Siniperca chuatsi at different developmental age were observed and described by histology sectioning, H.E and AB. PAS stainings. The results showed that at 15 days after hatching, there was a cluster of pyloric caeca began to develop on the left ventral side between the stomach and intestine. At 20 days after hatching, there was a cluster of pyloric caeca that developed on the right ventral side below the intestinal tract, and at 25 days after hatching, there was a cluster of pyloric caeca that developed on the right ventral side between the stomach and intestinal side, and the left ventral side below the intestine, respectively. At the age of 20, 30, 40, 50 and 60 days, the number of pyloric caeca was (25±2), (75±2), (123±4), (155±7) and (190±5), respectively. The number and the length of the folds and the thickness of the muscular layer of pyloric caecum increased with development age. The pyloric caecum was clustered by multiple branches, each of which produced two sub-branches in the middle section. Ⅱ type of mucous cell was widely distributed in the pyloric caecum, followed by type Ⅳ, there was no Ⅰ type mucous cell. The number of mucous cells on the base pyloric caecum was higher than the top part.