The invention provides a composite separating membrane and a preparation method and application thereof. The composite separating membrane comprises a bottom membrane, and is characterized in that the bottom membrane is attached to a
transition layer; the
transition layer consists of
metal organic frame materials. The invention also discloses a method for preparing the
composite membrane. The method comprises the following steps: sequentially and ultrasonically dispersing the
metal organic frame materials to form suspension; and
coating the suspension made of the
metal organic frame materials and a solution of separating layer materials on the bottom membrane to sequentially form the
transition layer and a separating layer. The separating membrane is simple in preparation method and is easy to control and can be used for the preparation process of various composite membranes in the separating membrane industry. Compared with a conventional
high polymer material transition layer, the composite separating membrane has high physical and
chemical stability and mechanical performance and has wide application prospects.