In this work, ZIF-9 membranes were successfully synthesized using temperature-switching synthesis method. Compared with the conventional hydrothermal synthesis at a constant temperature, this method could promote the growth of crystals on the support. Scanning electron microscopy (SEM) demonstrated that the obtained membranes had continuous and well-intergrown layer with a denser surface and better crystal size uniformity. As a result, gas separation performance was enhanced. It is also found that the properties of membrane can remain almost stable at a relatively broad range of operating temperature and trans membrane pressure drop, which is beneficial for the practical operation of membrane in the separation process. More importantly, this synthesis strategy can be conveniently extended to the preparation of other MOF membranes with improved performance.