This study was designed to evaluate the effects of dietary nickel chloride (NiCl2) on the splenic immunity in broilers by observing changes of cytokine mRNA expression and protein levels, immunoglobulin (IgA, IgG, and IgM) contents, and IgA+ B cell and T-cell numbers using the methods of qRT-PCR, flow cytometry (FCM), and ELISA. A total of 240 1-day-old avian broilers were equally allocated into four groups and fed on a corn-soybean basal diet as the control diet or the same diet supplemented with 300, 600, and 900 mg/kg NiCl2 for 42 days. The mRNA expression and protein levels of IL-2, IL-6, IL-10, IL-12, TNF-α/LITAF, IFN-γ, and IgA, IgG, and IgM contents were significantly decreased (p<0.05 or p<0.01) in the 300-, 600-, and 900-mg/kg NiCl2 groups when compared with those of the control group, which was consistent with the reduction of T-cell subset percentages and IgA+ B cell numbers in the 300-, 600-, and 900-mg/kg NiCl2 groups. The abovementioned results showed that dietary NiCl2 in excess of 300 mg/kg caused damage on splenocytes and splenic immune function. The results of the present study provided new experimental evidences for further study on the effect mechanism of NiCl2 on splenic immunity.