Abstract: In this study, the effect of immunosuppressant cyclophosphamide (CPM) on performance and incretion were investigated to discuss nutritionmetabolism characteristic in the condition of immunosuppression in broiler. 120 male commercial Arbor Acres broiler with similar body weight, randomly were divided into two groups（60×2）:Control group (C) and CPM groups (T). The birds in C and T groups were injected intraperitoneal with equiroluminal of 0.90% NaCl and CPM (10 mg/kg BW) at day 20, respectively. Other factors were same between two groups. Feed intake was recorded and full excreta were collected daily.Body weight of birds per pen were measured, at days 1, 3, 5, 8 and 13 after treatment, respectively, and blood of 4 randomly selected birds per group were obtained by heart puncture and the spleen, bursa Fabricii and thymus were weighted and these tissues at 1 day after treatment were restored in liquid nitrogen to examine the content of mRNA of IL-1β, IL-2 and IFN-γ in them.The level of GC, insulin, T3 and T4 in all serum collected were measured by radioimmunoassay (RIA) and proliferation of T and B cell were examined. The results were as follows: Compared to that of control groups, at day 1 after treatment, CPM decreased bursa Fabricii index, proliferation of B lymphocytes and the content of IL-1β mRNA in bursa Fabricii and the content of IFN-γ mRNA in bursa Fabricii and thymus significantly (P<0.05) CPM increased body weight and decreased feed intake and feed crude fat and crude protein apparent digestibility significantly (P<0.05). CPM decreased the content of GC and increased the level of insulin in serum significantly (P<0.05). Besides significant increase of body weight in T groups at day 3 after treatment, there were no significant differences of other parameter determined at other time (P>0.05) These results showed that CPM induced immunosuppression in which condition performance was improved and the incretion of GC was decreased while that of insulin was increased in broiler.