This paper reports on the scaling-up of a one-step methanol production process from the laboratory scale to the pilot scale. This lays the foundation for the industrialization of a one-step process for preparing DMM from methanol. After a long period of operation in the circulating fluidized bed, the Fe-Mo/HZSM-5 catalyst was shown to have high stability and carbon deposition resistance, and the regeneration effect of the circulating regeneration fluidized bed was better. In addition, in-situ DRIFTS was used to explore the effects of reaction time, the Mo-Fe ratio and carrier Si-Al ratio on the reaction and product distribution. It was found that the synergistic effect of oxidation centers and acid centers was the fundamental reason for the excellent catalytic performance of the Fe-Mo/HZSM-5 catalyst. And proposed the reaction mechanisms in the one-step synthesis of methylal via methanol oxidation.