To explore the effects of different concentrations of seaweed fertilizer on the antioxidant physiology characteristics and related gene expression level of Dendrobium officinale under low-temperature stress，D. officinale ‘Jing Pin No.1’ seedlings were sprayed with different dilution multiples seaweed fertilizer(500，1000，1500)on the leaves and treated with a low-temperature of 4℃. The results showed that under low-temperature stress，the 1000 dilution multiples of seaweed fertilizer treatment alleviated the damage of leaf cell and chlorophyll degradation，decreased the malondialdehyde(MDA)content，while they also induced the proline content，peroxidase(POD)，superoxide dismutase(SOD)，ascorbate peroxidase(APX)activity and POD，SOD gene expression level，but seaweed fertilizer treatments reduced the catalase(CAT)activity and CAT gene expression level. In the early stages of the recovery growth period after low-temperature stress，the seaweed fertilizer treatments significantly increased the activity of antioxidant enzymes than control，which improved the comprehensive antioxidative capacity of D. officinale seedlings during the recovery growth period. In summary，spraying a suitable concentration seaweed fertilizer could improve the ability of resisting low-temperature for D. officinale.