Objective To observe the effectiveness of treating essential thrombocytosis(ET) with Buyang Huanwu Decoction plus hydroxyurea. Methods 120 patients with ET were randomly divided into observation group(OG) and control group(CG). Patients from OG were treated with Buyang huanwu decoction plus hydroxyurea, while those from CG were given hydroxyurea. After 6 months, the treatment effectiveness indexes including symptoms in a sense of chinese medicine, cell counts and saffy were observed. Results Total effective rate of OG was higher than that of CG(P<0.05). TCM symptoms remission in OG group was better than that of CG(P<0.05). After treatment, blood platelet count and megakaryocyte count were decreased in two groups(P<0.05), and the difference between two groups was signiifcan(P<0.05). Conclusion The therapy combined Chinese and western medicine deals with ET is better than simple western medicine treatment.