Abstract: Continuous high temperature of 35℃ for more than 25 days in July 2022, and there is still an increasing trend of continuous high temperature days every year, which pose risks to submerged aquatic plants and crab farming. This study aimed to screen high-temperature tolerant aquatic plants in crab ponds and evaluate their effects when used as feed for juvenile Chinese mitten crabs (Eriocheir sinensis). Two experimental modules were conducted in this study. In the high-temperature tolerance screening experiment, five aquatic plant species, named as Alternanthera philoxeroides (Mart.) Griseb., Ludwigia peploides (Kunth) P.H.Raven, Elodea nuttallii (Planch.) H.St.John, Hydrilla verticillata (L.f.) Royle, Vallisneria natans (Lour.) Hara, were exposed to acute heat stress at 30, 35, and 38 °C for 72 h. Chlorophyll content and antioxidant indices (SOD, CAT, POD, H₂O₂, MDA) were measured in leaves and roots to compare species-specific heat tolerance. For the feeding experiment, this study using A. philoxeroides as a control, juvenile crabs were fed diets supplemented with L. peploides to investigate effects on hepatopancreas digestive enzyme activity (amylase, lipase, Na⁺/K⁺-ATPase), antioxidant status (T-AOC, GSSG, GSH), and appetite-related gene expression in eye stalks (gaba1, npy, leptin, crf) and Akt/TOR/4E-BP signaling pathway genes. Key findings: (i), Chlorophyll content of A. philoxeroides and L. peploides first increased and then decreased with rising temperature, whereas the other species showed continuous declines. (ii), L. peploides maintained high SOD and POD activity under heat stress, with moderate increases in H₂O₂ and root MDA, indicating strong antioxidant regulation. (iii), Feeding L. peploides significantly enhanced digestive enzyme activities and antioxidant capacity in juvenile crabs, increased expression of appetite-promoting genes (gaba1, npy), and reduced expression of appetite-suppressing genes (leptin, crf) and Akt/TOR/4E-BP pathway genes. In conclusion, both L. peploides and A. philoxeroides exhibit strong heat tolerance. L. peploides also exerts beneficial effects on juvenile crab appetite and metabolism, supporting its use as a preferred aquatic plant for crab ponds during juvenile stages and high-temperature periods.