NOVELTY - Decompression biodiesel producing device comprises an ester exchange reactor (3), a vacuum pump (10), a heat exchanger (8) and a crude product separator (6), where: the front half part of the ester exchange reactor is provided with a solid catalyst fixed bed (1), the bottom part is provided with a methyl alcohol distributor, the left upper part is provided with a raw material grease inlet, the upper opening is connected with the inlet of the vacuum pump and the right lower part is provided with a crude product discharge port. The heat exchanger is a tubular structure of the cylinder.    USE - Used as a decompression biodiesel producing device.    ADVANTAGE - The device: comprises a vacuum pump, which reduces the boiling point of methyl alcohol and the pressure of the whole system so that the ester exchange reaction can be performed at low temperature and pressure; and has low energy consumption and high raw material conversion ratio.    DETAILED DESCRIPTION - Decompression biodiesel producing device comprises an ester exchange reactor (3), a vacuum pump (10), a heat exchanger (8) and a crude product separator (6), where: the front half part of the ester exchange reactor is provided with a solid catalyst fixed bed (1), the bottom part is provided with a methyl alcohol distributor, the left upper part is provided with a raw material grease inlet, the upper opening is connected with the inlet of the vacuum pump and the right lower part is provided with a crude product discharge port. The heat exchanger is a tubular structure of the cylinder, where the left upper part is connected with the outlet of the vacuum pump and the bottom part is a reclaimed methyl alcohol discharge port. The middle upper part of the crude product separator is a cylinder, where: the lower part is a cone, the middle part on the left is provided with a crude product inlet, the right upper part is provided with a biodiesel discharge port and the bottom part is provided with a crude glycerol discharge port.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of the decompression biodiesel producing device.    Solid catalyst fixed bed (1)    Ester exchange reactor (3)    Crude product separator (6)    Heat exchanger (8)    Vacuum pump (10)