This study conducted a prospective, multicenter, one-arm clinical trial on the combination of leflunomide and steroid therapy for refractory skin Henoch-Schonlein Purpura in children on the basis of ethical principles. A one-year follow-up was conducted to evaluate the changes in the main indicators (frequency of rash recurrence) and secondary indicators (proportion of kidney damage, proportion of joint involvement, T lymphocyte subpopulations, and inflammatory factors) before and after treatment, Exploring the safety and effectiveness of leflunomide in the treatment of refractory skin type HSP in children, it is expected that leflunomide combined with conventional treatment can improve the remission rate of HSP children's skin purpura and reduce HSP recurrence. The research results are expected to bring new treatment methods and strategies for this group of patients.

Inclusion Criteria:

1. Age ranges from 1 to 18 years old;
2. Patients meet the HSP diagnostic criteria;
3. Refractory skin type HSP: Rashes are dense and large in area, often treated with antibiotics, antihistamines, calcium supplements, and glucocorticoids (2 mg/kg/d) for 5 days. The rash does not subside or fresh rash still appears, and frequently repeated more than 3 times during hospitalization.
4. Parents or guardians agree to treatment and sign a written informed consent form.

Exclusion Criteria:

1. Individuals who are allergic to leflunomide;
2. Concomitant severe underlying diseases (such as systemic malignancy, heart failure, liver and kidney failure, immune deficiency, severe infectious diseases, organ transplant surgery, or other current indications for emergency surgery);
3. Patients with other digestive system diseases;
4. Those who have previously used flumiphene in clinical trials;
5. Excluding purpura caused by drugs, infectious factors, and other autoimmune diseases.
6. Other situations where the researcher deems it inappropriate to participate in the study.