In this article, based on a combined chemical mechanism with detailed ethanol oxidization and NO production mechanisms, a single cylinder ethanol HCCI engine model was established using the software CHEMKIN. Comparing with experimental data, this model can well predict cylinder pressure and NO emission. By changing mole fraction of hydrogen peroxide in initial ethanol mixture at different conditions, the effect of hydrogen peroxide additive on ethanol HCCI engine performance was investigated. The results show that hydrogen peroxide can effectively improve cylinder pressure and advance heat release progress, without notably increasing NO production.