Nine different proportions of a group of bacteria, including Shewanella haliotis, Bacillus cereus, andAeromonas bivalvium were isolated from the gut of Pacific white shrimp, Litopenaeus vannamei. The shrimp werefed fodder with 109 cfu/g compound bacteria for 28 d using an orthogonal experimental design, and the effects ongrowth and innate immunity of the shrimp were assessed. Ammonia-nitrogen was adjusted to 26.67 mg/L withNH4Cl after 16 d, and ammonia-nitrogen resistance of the shrimp was tested. The results show that shrimp growthimproved after the 28 d probiotic feeding regime, compared to that of the control (P<0.05), and the 6︰1︰3 proportionwas better than the others. These results suggest that the compound bacteria promoted growth through secretionof nutrients and improved feed digestibility. Moreover, the positive effects of the compound bacteria oninnate immunity and ammonia-nitrogen resistance of L. vannamei were eventually expressed as improved growth.The activities of acid phosphatase (ACP), alkaline phosphatase (ALP), and total superoxide dismutase (T-SOD)were also enhanced compared to those in the control (P<0.05), but the effects were different. The 2︰3︰3, 4︰2︰3,and 6︰1︰3 proportions increased ACP activity significantly more than the others (P<0.05), and the 4︰2︰3 and6︰1︰3 proportions increased ALP activity significantly more than the others (P<0.05). The 2︰1︰1 proportionincreased T-SOD activity significantly more than the others. No changes in shrimp serum lysozyme activity weredetected in any of the bacteria-tested groups compared to the control. The results that serum ACP, ALP, and T-SODactivities were enhanced compared to the control show that the different proportions of bacteria positively affectedshrimp innate immunity. In addition, the 4︰3︰1 and 6︰3︰2 bacterial proportions significantly enhanced ammonia-nitrogen resistance in Pacific white shrimp (P<0.05). These results show that the compound bacteria hadpositive effects on ammonia-nitrogen resistance of L. vannamei and suggest that ammonia-nitrogen resistance isassociated with the immune system.