ABSTRACT High-resolution two-dimensional numerical simulations are performed to investigate n-heptane/air autoignition process under different initial temperatures with varied levels of temperature fluctuations. It is found that temperature fluctuation has an important impact on the autoignition process, and its effects depend on the initial mean temperature. When is located at the upper turning point of the negative temperature coefficient (NTC) regime, as the temperature fluctuation increases, the autoignition mode evolves from a single-stage ignition mode controlled by high-temperature chemistry (HTC) to a mode characterized by the coexisting of multi-stage and single-stage ignition. Both the first-stage heat release and ignition delay increase, but the overall heat release and the total ignition delay decrease. In the presence of a large temperature fluctuation, the low-temperature chemistry (LTC), and HTC reactions, single-stage and two-stage ignitions could coexist in the domain. Chemical explosive mode and sensitivity analyses are performed to identify the reaction mode and the key element reactions in the mutli-stage autoignition process. The temperature fluctuation has a significant promotion effect on the overall ignition except when is located at the lower turning point of the NTC regime. Overall, the NTC phenomenon is weakened under the influence of temperature fluctuation, approaching to zero temperature coefficient (ZTC) phenomenon.