Objective To investigate the curative effect of methotrexate in treating systemic lupus erythema-tosus(SLE). Methods The chosen outpatients were divided into 2 groups,group A(28 cases) :MTX combined with small dosage of prednisone (prednlsone 10mg/d) ; group B (20 cuses) : medium dosage of prednisone (prednisone 30rag/d). Observation includes SLE disease activity index(SLEDAI) ,relapse while dosage of prednisone was reduced to small amount and drug side effects. Results The SLEDAI score of group A was reduced from (9.4±2.1) to (4.1±0.9) ,and group B from (8.6±2.5) to (4.0±1.0). Compared the result of before and after treatment be-twcen the two groups, the curative effect is obvious (P<0.01). However, there was no significant difference of efficacy between the two groups(P>0.25). While dosage of prednisone was reduced to 10mg/d ,there were 8 cases of relapse in group B,and only 3 cases in group A during the entire observation period. The difference is significant (P<0.025). The side effect of group A is gastrointestinal reaction and for B is mainly the cushing syndrome. Conclusion MTX is an effective treatment fw the light and medium activity SLE,and can reduce the dose of prednisone, prevent long-term using large dose of prednisone which will cause side effect.