Based on the CHEMKIN PRO software, this paper selects the NUI 2016 mechanism to study methane-n-heptane dual fuel. The two-stage ignition characteristics of methane-n-heptane dual fuel under medium and low temperature conditions were investigated, and the corresponding chemical kinetic analysis was carried out. The results show that the two-stage ignition behavior occurs when the initial temperature is lower than 750 K, and the two-stage ignition process shows a certain NTC (negative temperature coefficient) behavior; with the increase of n-heptane content, the two-stage ignition delay time is reduced, and the effect is most significant when the n-heptane content below about 75%. The related chemical kinetic analysis shows that the methane is mainly consumed in the second stage, the n-heptane is oxidatively decomposed in the first stage and during the second stage it is completely oxidized. By the reaction path analysis, it is found that the radicals and intermediates produced by the first stage reaction increase the activity of the system and promote the ignition process of the dual fuel.