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[Display omitted] • Flammability limits of the new binary mixture R1234ze(E)/R32 was measured. • Oxidative decomposition and interaction mechanisms of R234ze(E)/R32 were studied. • R32 decomposes preferentially and R1234ze(E) is more likely to react with radicals. • CF 3 plays an important role in R1234ze(E) inhibiting flammability of R32. At present, mixed working fluids have received increasing attention due to their excellent comprehensive performance. Among them, R1234ze(E) (trans -1,3,3,3-tetrafluoropropene) and the R32 (difluoromethane) with excellent thermal properties can form a safe and environmentally friendly new mixture through advantageous complementarity. In this paper, the flammability of the binary mixture R1234ze(E)/R32 mentioned above was studied. Firstly, the flammability limits and critical concentration inhibition ratio of R1234ze(E)/R32 were tested at different ratios. Then, based on density functional theory (DFT), the interaction mechanism between the two components in the mixture was analyzed. The results show that with the increase of R1234ze(E), the flammable limit range becomes narrower. In the early stage of the reaction between R1234ze(E)/R32, R32 preferentially breaks the bond to generate H and F radicals, but the reactions between R1234ze(E) and free radicals are dominant. CF 3 radical is an important free radical for R1234ze(E) to inhibit the flammability of R32. The research results will have guiding significance for the internal interaction mechanism of the flammability of new binary mixtures and their safe applications. [ABSTRACT FROM AUTHOR]