Aim To investigate the effects of insulin on expression and secretion of tumor necrosis factor-α (TNF-α) protein of human peripheral blood mononuclear cells and the effects of Pravastatin. Methods The human peripheral blood mononuclear cells were derived from healthy volunteer's vein blood by dendity centrifugation using Ficoll and cultured in RPMI 1640 medium containing 10% autologous serum, and then added human insulin, Pravasatatin and mevalonate to continue culture for 48 h, the levels of TNF-α protein in cells and in supernatant were tested by Western blot and ELISA assay. Results Insulin stimulation resulted in significantly elevated levels of TNF-α protein in mononuclear cells and the supernatant of cells culture in dose-dependent, however, after incubated with insulin plus Pravastain, the levels of TNF-α protein in cells and the supernatant were lower, which effects could be diminished by added mevalonate. Conclusion Insulin can increase the expression and secretion of TNF-α protein of human peripheral mononuclear cells and its effects can be inhibited by Pravastatin, which indicats that the cardioprotective effects of Pravastatin on diabetes patients might be partially associated with inhibiting inflammation mediated by insulin.