NOVELTY - Continuous recycle reactor for producing biodiesel by performing esterification reaction of solid acid and methanol, comprises a cylinder body (10) whose lower part is set with an oil inlet (8). The upper part of the cylinder body is equipped with a gas phase methanol outlet (1). The gaseous phase methanol outlet is directly connected to a condenser (4). The inner wall of the cylinder is equipped with a circular arc convex groove (3). The circular arc convex groove edge is provided with a filter screen. The inner wall of the cylinder body is provided with an oil outlet.    USE - The reactor is useful for producing biodiesel by performing esterification reaction of solid acid and methanol.    ADVANTAGE - The gaseous phase methanol outlet of the reactor can easily recover methanol by the methanol recovery device. The oil outlet achieves continuous discharge of oil. The reactor is easy to operate, and economical; guarantees high acid value of oils and fats in biodiesel; continuously recycles the un-reacted methanol; and promotes large-scale development and production of biodiesel.    DETAILED DESCRIPTION - Continuous recycle reactor for producing biodiesel by performing esterification reaction of solid acid and methanol, comprises a cylinder body (10) whose lower part is set with an oil inlet (8). The upper part of the cylinder body is equipped with a gas phase methanol outlet (1). The gaseous phase methanol outlet is directly connected to a condenser (4). The 1/20th to 1/10th part of the inner wall of the cylinder is equipped with a circular arc convex groove (3). The circular arc convex groove edge is provided with a filter screen. The 1/20th to 1/10th part of the inner wall of the cylinder body is provided with an oil outlet. The oil outlet is directly connected to the circular arc convex groove. The circular arc convex groove is connected to the cylinder body which is set with a pipe coil heater. The cylinder body is provided with a heat insulating jacket.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of the continuous recycle reactor for producing biodiesel by performing esterification reaction of solid acid and methanol.    Gaseous phase methanol outlet (1)    Circular arc convex groove (3)    Condenser (4)    Oil inlet (8)    Cylinder body (10)