The phyllosoma larvae（ Ⅰ - Ⅳ ） of Patudirus stimpsoni of early development were collected from marine farm of Fisheries College of Jimei University from July to Sep. from 2000 to 2001. The histology, histochemistry and ultrastructure of their hepatopancreas were studied with light and electron microscopes. The results show that the hepatopancreas are made of two parets （right and left） and each part can be divided into three lobes that consist of many hepatopancreatic tubules, which increases in length and amount with the development of larva. Hepatopancreas connects the pyloric stomach and the midgut with two common gland duct （right and left）. The epithelium cells of hepatopancreatic tubules are classified into blister-like cells （B-cells）, resorptive cells （R- cells）, fibrillar cells（F-cells） and embryonic cells（E-cells） based on structure and function. The surface of all type cells has microvilli and these cells are located on a thin basement membrane. B-cells are mainly located in the proximal regions of the tubules, their volumes are the biggest and shapes are not regular, nuclei are crescent. B-cells have a large digestive vacuole, the denes cytoplasm, pinocytofic vesicles, small mitochondda exist in an apical complex body between the microvilli and large digestive vacuole. There are rough endoplasmic reticulum（RER） in basement of the cells. R-cells are the most numerous cell type, their nuclei are near round and located in the basement of cells. In some R-cells（ called Rl-cell）,no vacuoles are observed while some R-cells（ called R2-cell）have many vacuoles（under light microscope）. Mitochondria with moderate electron density matrix are developed and have many ridges, and RER and free ribosome are rich in Rl-cells where plnocytotic vesicles and dense granules were rarely observed. But in R2-cells, electron density of mitochondria is low and ridges are a few, there is the extensive and well-developed smooth endoplasmic reticulum （SER） containing material of high density in the basal region of the cell, some vesicles appeared around Golgi bodies and lipid droplets are a few or are forming in R2-cells. F-cells are mainly located in the middle regions of the tubules and scattering among B-cells and R-cells. It is strongly basophile, their nuclei are large and located in the middle regions of cells. RER, mitochondria and ribosome are very rich and zymogen granules aggregated in the apical cytoplasm. E-cells are located in the blind end of the tubules and undifferentiated, their volumes are small and a round or oval nucleus exists in middle regions of cells, and show a high ratio of nucleus to cytoplasm, cytoplasmic organelles are undeveloped in the E-cells. The study of histochemistry showed that four types of hepatopancreatic cells contained generality polysaccharides; there are some glycogen and lipid droplets in R-cells; the proteinic content is rich in the F-cells but less in other type of cells. The relation between the structure and function of four types of hepatopancreatic cells of the phyllosoma larvae was studied too in this paper. It is generally believed that the main absorptive and digestive function of the gland is carried out by the B-cells which ingest nutrients by pinocytosis and process them in a large digestive vacuole;the R-cells absorb soluble material from the lumen by diffusion and store them as lipid and glycogen in the cytoplasm;F-cells synthesize zymogen granules which are exocytosed into the tubule lumen and carry out function of extracellular digestion. E-cells divide by mitosis to differentiate into other tvoe of cells.