OBJECTIVE: To investigate effect of Qushi Xiezhuo formula(QSXZF) on axial spondyloarthritis(AxSpA)with a high incidence of monosodium serum urate(MSU) crystal deposition.METHODS: In this prospective cohort study, 62 AxSpA patients diagnosed with MSU crystal deposition from October 2012 to July 2015 were recruited for follow-up observation for 1 year after discharge from the hospital.Patients were divided into a case group with QSXZF treatment and a control group without any interventions.X-ray and dual-energy computed tomography were used to assess structural damage in the pelvis and sacroiliac joint and the volume of the MSU crystals.The Wilcoxon ranksum test and Fisher's exact test were used to compare the proportion and distribution between the groups.RESULTS: A decrease in C-reactive protein(CRP)level, relief from back pain, and an increase in MSU crystal depositions were found in control patients.Compared with the control group, QSXZF reduced CRP levels and back pain to a greater extent, as well as reduced erythrocyte sedimentation rate levels,serum uric acid levels, Ankylosing Spondylitis Disease Activity Score, morning stiffness and MSU crystal deposition.CONCLUSION: QSXZF can lower progress of radiogrphaic grade at sacroiliac joint in AxSpA/AS patients with MSU crystal deposition by decreasing the inflammation response and reducing the serum uric acid and volume of MSU crystal deposition in sacroiliac joint.The above process may be attributed to the relieving the Qi-movement disturbance in the body, and eliminating turbidity and dampness by QSXZF.