In order to investigate the effects of seaweed extracts on plant under heat(30℃)stress，the yield，fruit quality，hormone levels，and antioxidant system were analyzed using cherry radish(Raphanus sativus L. var. radculus pers)by pot experiment. Under artificial climate incubator conditions，the cherry radish was incubated in base material under the adding seaweed extracts concentrations of 100.0 and 200.0 mg·L-1( SWE-1，SWE-2 treatment，respectively)，using water as control(CK)and the concentration of 66.7 mg·L-1 brassinolide as the positive control (BHG) . The results showed that the seaweed extracts with the concentration of 100 and 200 mg·L-1 could effectively alleviated the stress effect of high temperature on the growth of cherry radish，and treatment with SWE-2 had the best effect. Compared with CK treatment，the fruit fresh weight of SWE-2 treatments was boosted significantly by 180.0%，and the soluble protein contents were boosted significantly by 35.2%； the SPAD readings were boosted significantly by 16.8%，the nitrate reductase activity was boosted significantly by 57.7%，and auxin content was boosted significantly by 145.4%；abscisic acid content was decreased significantly by 42.0%， the malondialdehyde content was decreased significantly by 59.2%，the activity of glutathione reductase was boosted by 15.7%，and the activity of ascorbic peroxidase was boosted by 9.4%. In addition，compared with BHG treatment，the fruit fresh weight of SWE-2 treatment was boosted significantly by 43.5%，the soluble protein content was boosted significantly by 49.6%，and the vitamin C content was boosted significantly by 68.4%. Nitrate reductase activity of leaves was boosted significantly by 17.1%. The malondialdehyde content decreased significantly by 41.7%，the activity of glutathione reductase was boosted significantly by 23.7%，and the activity of ascorbic peroxidase was boosted significantly by 29.9%，the activity of catalase was boosted significantly by 503.1%，which proved that the SWE treatments were more effective than the BHG treatments on alleviating the damage caused by heat stress. In conclusion，the application of seaweed extract can not only significantly enhance the resistance of cherry radish to heat stress，but also significantly enhance its yield and quality. This study provides theoretical support for the scientific application of seaweed extract in the secure production of fruits and vegetables.