The experiment was conducted to investigate the effects of dietary threonine (Thr) on growth performance, and muscle growth, protein synthesis and antioxidant related signaling pathways of hybrid catfish Pelteobagrus vachelli♀ × Leiocassis longirostris♂. The total of 1200 fish (14.19 ± 0.13 g) were randomly distributed into six groups with four replicates each, fed six diets with graded level of Thr (9.5, 11.5, 13.5, 15.4, 17.4, and 19.3 g kg-1 diets) for 56 days. Results showed (P< 0.05) that dietary Thr (1) increased percent weight gain (PWG), specific growth rate (SGR), feed efficiency (FE), and protein efficiency ratio (PER); (2) up-regulated growth hormone (GH), insulin-like growth factor 1 (IGF-1), proliferating cell nuclear antigen (PCNA), myogenic regulation factors (MyoD, Myf5, MyoG, and Mrf4), and MyHC mRNA levels; (3) increased muscle protein content via regulating AKT/TOR signaling pathway; (4) decreased malondialdehyde (MDA) and protein carbonyl (PC) contents, increased CAT, GST, GR, and GSH activities, up-regulated mRNA levels of antioxidant enzymes related to NFE2-related factor 2 (Nrf2) and γ-glutamylcysteine ligase catalytic subunit (GCLC). These results suggest that Thr has potential role to improve muscle growth and protein synthesis, which might be due to the regulation of GH-IGF system, muscle growth related gene, antioxidative capacity, and protein synthesis related signaling pathways. Based on the quadratic regression analysis of SGR, the Thr requirement of hybrid catfish (14.19–25.77 g) was estimated to be 13.77 g kg-1 of the diet (33.40 g kg-1 of dietary protein).