Six isonitrogenic and isoenergy diets were designed to investigate the effects of tea tree essential oil and astaxanthin on growth performance, antioxidant capacity, and immune-related gene expression of Proambarus clarkii: basal diet (CT), astaxanthin 50 mg/kg (AS50), 50 mg/kg astaxanthin and 50 mg/kg tea tree oil (AS50+AST50), 50 mg/kg astaxanthin and 100 mg/kg tea tree oil (AS50+AST100), 50 mg/kg astaxanthin and 200 mg/kg tea tree oil (AS50+AST200), and 50 mg/kg astaxanthin and 400 mg/kg tea tree oil (AS50+AST400). An 8-week culture experiment was conducted. After astaxanthin was added, the feed conversion ratio of AS50 was significantly decreased (P＜0.05), the final average weight, weight gain rate, and specific growth rate with the increased trend showed no significant differences with the CT group (P ＞ 0.05), and the total antioxidant capacity (T-AOC) in hemolymph and intestinal tissue was significantly increased compared with the CT group (P＜0.05). The content of malondialdehyde (MDA) in hemolymph and intestinal tissue was significantly decreased (P＜0.05). The expression of the Crustin, Astacidin, CuZnSOD, and HSP70 genes was significantly increased compared with the CT group (P＜0.05). After tea tree essential oil and astaxanthin were added, the final body weight, weight gain rate, specific growth rate, and T-AOC in AS50+AST100 were significantly higher than in AS50 and CT groups (P＜0.05), and the intestine MDA content was significantly lower (P＜0.05). The expression levels of the Crustin and Astacidin genes in intestinal tissues increased with the increase of tea tree essential oil content and was significantly lower for the combination group of AS50 and AST50 than in the other groups (P＜0.05). The expression level of CuZnSOD was first increased and then decreased with the increase of tea tree oil concentration and was significantly higher in the AS50+AST50 and AS50+AST100 groups than in the other groups (P＜0.05). The expression of HSP70 were significantly higher than those in the CT group (P＜0.05). The results showed that adding a combination of 50 mg/kg astaxanthin and 100 mg/kg tea tree oil to the diet could improve antioxidant and immune capacity and promote the growth of Procambarus clarkii.