This is a prospective,randomized,open-label,multi-center clinical trial. The aim of this study is to test the efficacy of GC(gluco-corticosteroid)+HCQ(hydroxychloroquine) and GC(glucocorticosteroid)+CTX(cyclophosphamide) with sequential AZA(azathioprine) in the induction and maintenance therapy of severe thrombocytopenia in SLE patients.