SAPO-34 molecular sieve has the problems of low olefin selectivity and easy carbon deposition of acidic sites in MTO reaction.In this article, Metal Co was introduced into the pores of SAPO-34 through equal volume impregnation method, and the effect of Co addition on the catalytic performance and carbon deposition behavior of Co/ SAPO-34 catalyst in the MTO reaction was systematically investigated. The results indicate that metal Co can serve as a central site for dehydrogenation reactions, weaken hydrogen ion transfer, inhibitthe generation of alkanes, and effectively improve the selectivity of olefins in the reaction. At the same time, the introduction of Co metal can also precisely regulate the strength of acid centers on the surface of SAPO-34, increase the ratio of weak acid to strong acid, thereby weakening the carbon deposition effect of strong acid centers and inhibiting the deactivation of catalyst. By combining characterization methods such as NH3-TPD, H2-TPD, BET, TG, XPS, GC-MS, etc., this paper deeply explored the carbon deposition behavior ofCo/ SAPO-34 catalyst in MTO reaction. It is found that key carbon deposition precursors like polymethyl-substituted benzene are preferentially deposited on micropores and strong acid sites, and significantly promote the generation of polycyclic aromatic hydrocarbons. The relatively large pore volume and appropriate weak acid concentration can synergistically promote the decomposition and transformation of carbon deposition precursors, inhibiting the formation of hard coke. The calculation of carbon deposition rate shows that Co0.5 / SAPO-34 withappropriate acidity and pore structure has the highest methanol conversion rate, low-carbon olefin selectivity and the longest catalytic life.