Aim. Dermatophytosis is one of the main fungal diseases in humans and animals all over the world. Galla chinensis, a traditional medicine, has various pharmacological effects. The goal of this study was to evaluate the treatment effect of Galla chinensis solution (GCS) on dermatophytosis‐infected dogs (Microsporum canis, Microsporum gypseum, and Trichophyton mentagrophytes, resp.). Methods. The treatment effects of GCS were evaluated by mycological cure rates and clinical score comprised of three indices, including inflammation, hair loss, and lesion scale. Results. The results showed that, in the three models of dermatophytosis, GCS significantly (P < 0.05) improved skin lesions and fungal eradication. GCS (10% and 5%) had higher efficacy compared to the positive control (Tujingpi Tincture). The fungal eradication efficacy exceeds 85% after treatment with GCS (10%, 5%, and 2.5%) on day 14. Conclusion. The GCS has antidermatophytosis effect in dogs, which may be a candidate drug for the treatment of dermatophytosis.