Abstract: To explore the structure of the spleen of Pelteobagruvs vachelli and the location of its blood-spleen barrier, we observed its spleen in morphology, size, histology and in vivo staining. The results show that the spleen of P. vachelli was located in the middle of the abdominal cavity with dark red colour, and the spleen body index was 0.120%–0.273%. Paraffin sections of healthy spleen were prepared and stained with HE and modified James, and the microscopic observation reveals that the spleen tissue was mainly composed of underdeveloped capsule system, unclear boundary between red and white pulp, and fibers that were composed of reticular fibers and collagen fibers. Reticular fibers were mainly located around the splenic cord and ellipsoid; collagen fibers were mainly located in the splenic cord. We applied Trypan blue in vivo staining method to explore the position and function of the blood-spleen barrier, and found that Trypan blue was mainly located in the ellipsoid endothelial cells of the spleen, and first appeared at 4^th hour after injection. It accumulated in the ellipsoid gradually along with time, and the number increased significantly after 24 h, and continued to increase until 72^nd hour. It is shown that the ellipsoid endothelial cells are an important component of the blood-spleen barrier.