Background A painless and effective treatment of childhood epistaxis is needed. Objective To observe the effectiveness of low-intensity diode (Lid) laser in treating epistaxis complicated with allergic rhinitis in children. Methods Our study is a prospective, randomized, controlled, registry trial (NO. 202001201) involving 44 recurrent epistaxis children (<14 years old) with or without Allergic Rhinitis (AR) in our hospital. They were divided randomly into the Laser and Control groups. The Laser group was treated with Lid laser (wavelength 635 nm, power 15mW) for 10 min after nasal mucosa was moistened with normal saline (NS). The Control group moistened their nasal cavities with NS only. Children in two groups complicated with AR were given nasal glucocorticoids for 2 weeks. The effectiveness of Lid laser in treating epistaxis and AR were compared between the two groups after treatment. Results After treatment, the effective rate of the Laser group in epistaxis (23/24, 95.8%) was higher than the Control group (16/20, 80%) (p < .05). The VAS scores of the children complicated with AR in the two groups both improved after treatment, however, the variation of VAS score (3.02 ± 1.50) in the Laser group was greater than the Control group (1.83 ± 1.56) (p < .05). Conclusion As a safe and efficient method, Lid laser treatment can effectively alleviate epistaxis and inhibit symptoms of AR in children.