The present study was conducted to investigate the effects of dietary crude algae extract from Ulva lactuce and Sarcodia montagneana on the innate immune response in white shrimp (Litopenaeus vannamei). White shrimp (10-12 grams) were fed for 60 days, including the control group, 1% Ulva extract group, 2% Ulva extract group, 1% sea fungus extract group, and 2% sea fungus extract group. The total haemocyte count (THC), superoxide dismutase (SOD) activity, lysozyme activity and phenoloxidase activity (PO) were analyzed at days 0, 2, 4, 6, 10, 20 and 30. The results showed that the concentration of THC and SOD and activity of lysozyme and PO in white shrimp at rude algae extract group was higher (p < 0.05) than those of the control group, and reached the highest point on the 4th and 30th day after feeding respectively However, the concentration of THC and SOD dismutase began to decrease on the 6th day after feeding, and the lysozyme activity also weakened after the 4th day. In addition, Vibrio alginolyticus was used for the challenge test. The white shrimps were fed with a feed containing 1% Ulva extract group, 2% Ulva extract group, 1% sea fungus and 2% sea fungus extract for 30 days, and after feeding the feed challenges were performed on days 0, 2, 4, 6, 10, 20, and 30. The results showed that the clearance efficiency and survival rate of the algae extract group were higher than those of the control group.