Abstract: In order to study the function of kdm4aa on low temperature tolerance of zebrafish, the levels of kdm4 families in kdm4aa^-/- zebrafish and the level of kdm4aa in wild type（WT） zebrafish treated by low temperature were detected by real time quantitative PCR. The locomotor ability of kdm4aa^-/- juvenile fish at low temperature was detected by the behavior trajectory tracking system of zebrafish. The low temperature tolerance of kdm4aa^-/- zebrafish was measured by a stepwise cooling method. Reactive oxygen species（ROS）, adenosine triphosphate（ATP）, gamma histone H2A.X（γH2A.X）, and microtubule-associated protein 1 light chain 3（LC3） levels in kdm4aa^-/- zebrafish were determined by DCFH-DA fluorescent probe, ATP detection kit and western blot, respectively. Real time quantitative PCR results showed that compared with WT zebrafish, the mRNA levels of kdm4ab and kdm4b in kdm4aa^-/- zebrafish were significantly increased, while no significantly different of kdm4c was observed. The detection of zebrafish behavior trajectory tracking system showed that the movement distance of juvenile zebrafish increased significantly after kdm4aa knockout at a low temperature of 18 ℃. At a low temperature of 8 ℃ mRNA level of kdm4aa in wild type zebrafish was significantly increased. Compared to WT zebrafish, the median lethal time LT₅₀ of kdm4aa^-/- zebrafish was significantly decreased after low temperature treatment（P＜0.000 1）; ROS level was significantly increased（P＜0.000 1）; ATP content was significantly decreased（P＜0.01）; The level of γH2A.X protein increased; LC3 protein levels decreased. These results showed that ROS accumulation of kdm4aa^-/- led to decreased ATP synthesis and increased DNA damage, and the autophagy ability of kdm4aa^-/- zebrafish was decreased, thus reducing the low temperature tolerance of zebrafish.