To evaluate the efficacy of etanercept in the treatment of active ankylosing spondylitis (AS) with enthesitis and explore an easy and accurate scoring method.We designed this 12-week double-blind, placebo-controlled, randomized clinical study in active AS patients. The first part was a 6-week placebo-controlled period that patients received etanercept or placebo, followed by a 6-week open-label period that all patients received etanercept. At week 0, 2, 4, 6, 8, 10, 12, the scores of enthesitis were recorded. The primary efficacy endpoint was the Mander Index in the two groups. We compared the Maastricht AS Enthesis Score (MASES) index, Spondyloarthritis Research Consortium of Canada (SPARCC) index, Berlin index and San Francisco index with the Mander Index.A total of 127 patients were included with 92 in the etanercept group and 35 in the placebo group. In etanercept group there were 25, 41, 47 patients without enthesitis at week 2, 4, 6 separately. At week 12, more than 70% patients' enthesitis in two groups turned negative. The primary endpoint, as the Mander Index at week 6, was achieved by 0(0, 2) score in the etanercept group compared with 1(0, 3) score in the placebo group (P = 0.0286). Among the four Indexes, the San Francisco Index was the one most correlated with the Mander Index.Etanercept can improve the symptoms of enthesitis fast and significantly. In clinics, the San Francisco Index is easier to operate and more accurate for assessment.