The invention discloses a recombinant gene which enhances the ability of fish to tolerate low dissolved oxygen (DO) stress and the use thereof. Carp β-actin gene promoter is used as a promoter and Vitreoscilla hemoglobin gene is used as a target gene, so as to construct the recombinant Vitreoscilla hemoglobin gene driven by carp β-actin promoter. The modeling organism zebrafish is used as the research object, and the recombinant gene is microinjected into zygotes of zebrafish. After PCR screening and 156 h low DO stress test, transgenic fish are obtained with a survival rate of 92%, which is significantly different from the survival rate of 65% of the control fish group. The vhb transgenic zebrafish obtain hypoxia tolerance. When the recombinant gene is applied to the economically farmed species, i.e., blunt snout bream (Megalobrama amblycephala) and common carp (Cyprinus carpio L.), it enhances their hypoxia tolerance as well. Such genetically improved breeding technique may be widely used for breeding new excellent farmed species with the hypoxia tolerance.