SAPO-34/kaolin microspheres catalysts (SCKMs) were in-situ hydrothermally synthesized onto the NaOH-pretreated calcined kaolin microspheres (CKMs). The effect of the NaOH concentration within 2%~10% on the physicochemical properties of CKMs and the ensuing synthesized SCKMs were characterized by means of XRD, XPS, SEM, low-temperature N2 adsorption. The results showed that, NaOH solution had obvious effects on the chemical composition and the morphologies of the CKMs, and then the properties of the in-situ synthesized SAPO-34 catalysts. In comparison, the optimal NaOH concentration was 4%. For the MTO reaction catalyzed by the prepared 4-SCKM catalyst, 100% methanol conversion, 89.8% light olefins selectivity, 964 min lifetime have been obtained, which are better than that of the SAPO-34 catalysts not synthesized by in-situ method.