It is important to inhibit the spontaneous combustion of lignite for its safe transportation and efficient utilization. Shengli lignite was treated with a NaOH solution and the as-prepared coal samples were extensively characterized by SEM-EDS, XRD, FT-IR, XPS, and Raman spectra techniques. The combustion properties of NaOH treated lignite were determined by TGA. The results show that NaOH treatment played a significant inhibitory effect on the combustion performance of Shengli lignite. The NaOH treated lignite showed two weight loss temperature regions. The temperature corresponding to the maximum combustion rate of Shengli lignite after the NaOH pretreatment was about 350-400 degrees C, higher than that of untreated sample, indicating that NaOH treatment significantly decreased the combustion reactivity of Shengli lignite. FT-IR and XPS analyses identified the analogous sodium polycarboxylic acid, originating from the crosslinking combination of carboxyl functional groups with NaOH. It is deduced that the suppressing effect of NaOH treatment on the combustion performance of lignite maybe attributed to the higher stability of analogous sodium polycarboxylic acid.