NOVELTY - Device for preparing biodiesel from mesoporous solid base catalyst, comprises a first ester exchange reaction column (4), a second ester exchange reaction column (7), a first separator (5), a second separator (10) and a biodiesel refining device (11). The top of the separator is connected to the top of the first ester exchange reaction column through a pipeline. The sidewall upper part of a material outlet is connected with the material inlet of the second ester exchange reaction column. The top of the second separator is connected with the second ester exchange reaction column.    USE - The device is useful for preparing biodiesel from mesoporous solid base catalyst.    ADVANTAGE - The device: has high biodiesel conversion rate, low production cost, simple operation control; and is less corrosive. The catalyst in the device can be recycled.    DETAILED DESCRIPTION - Preparing device for mesoporous solid alkali catalyzed biodiesel, comprises a first ester exchange reaction column (4), a second ester exchange reaction column (7), a first separator (5), a second separator (10) and a biodiesel refining device (11). The top of the separator is connected to the top of the first ester exchange reaction column through a pipeline. The sidewall upper part of a material outlet is connected with the material inlet of the second ester exchange reaction column through the pipeline. The top of the second separator is connected with the second ester exchange reaction column through the pipeline. The sidewall of the material outlet is connected with the material inlet of the biodiesel refining device through the pipeline. The material inlet of the first ester exchange reaction is connected at the bottom of an oil and methanol feeding pipe. The bottom of the first separator, second separator and biodiesel refining device are connected with a by-product recovering system through the pipeline.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of the device for preparing biodiesel from mesoporous solid base catalyst (Drawing includes non-English language text).    First ester exchange reaction column (4)    First separator (5)    Second ester exchange reaction column (7)    Second separator (10)    Biodiesel refining device (11)