Sinilabeo decorus tungting is a category of endangered fish that urgently requires resource protection. A histological study of the digestive system of larvae must be required to improve the survival rate of the artificial larvae of S. decorus tungting. In this study, the digestive system of S. decorus tungting from 2 to 80 days post-hatch (DPH) was studied using tissue sectioning technique, HE (hematoxylin-eosin) staining, and histochemical staining. The initial digestive system appeared to have a differentiated buccopharyngeal cavity and intestine at 2 DPH; However, the buccopharyngeal cavity was not opened outward. Further, hepatocytes closely surrounded the foregut and formed the hepatic cord. At 4 DPH, the gastrointestinal epithelial cells began to differentiate functionally, and the hepatocyte mass increased accordingly, filling between the yolk sac and digestive tract with light cytoplasmic staining and hepatic sinusoids initially. The digestive tract was connected, and the larvae were found to have entered the endo-exotrophic period. At 6 DPH, the cleft of the mouth deepened, assuming the shape of “＞,” and the snout was gradually shaped with mucus cells. The callose pad of the throat was keratinized, and the mucosal epithelium of the branchial arch was thickened. Mucus cells and taste buds were initially observed. The muscular layer of the esophagus was found to become thicker, with circular muscles as the major type. Several vacuoles were formed between hepatocytes, which became smaller. There were folds and striated margins on the intestinal epidermis. Further, the folds from the foregut to the hindgut became shorter as the goblet cells increased. At 9 DPH, the muscular layer of the posterior pharyngeal callose pad was identified, and the mucosal layer on the opposite side of the callose pad began to sag and form folds. The esophageal circular muscle developed; however, the longitudinal muscle did not manifest. Goblet cells were distributed in the intestine and the posterior segment to a greater extent. At 10 DPH, the lip cells displayed a keratinization trend, and the comb processes were formed on the surface of the callose pad. At 13 DPH, the yolk sac was completely absorbed, and the endo-exotrophic period transitioned to the exogenous nutrition period. At 43 DPH, the structures of the oropharyngeal cavity, gill, and intestine aligned with those of adult fish and gradually developed and improved as the fish grew. Herein, the development process for the digestive system of larvae and juveniles was further divided into three stages: endogenous nutrition period, endo-exotrophic period, and exogenous nutrition period. The change in feeding habits was found to be relative, and the digestive function was found to improve accordingly.