NOVELTY - A method for producing biodiesel by using seeds of soapberry comprises: (1) adding seeds of soapberry in the reactor with cutting and mixing device; (2) adding alcohol and fatty acid methyl ester, cutting and mixing; (3) adding alkalescent material; (4) preparing potassium hydroxide (KOH) or sodium hydroxide (NaOH)-methanol solution as the catalyst, adding in the suspending liquid (3), reflowing; (5) cooling; (6) standing and separating to remove the subsidiary product; (7) distilling, recovering the short chain alcohol; and (8) obtaining the biodiesel by atmospheric distillation.    USE - The method for producing biodiesel by using seeds of soapberry is useful for burning fuel technical field.    ADVANTAGE - The cetane number of biodiesel is high, and the solidifying point is low; it is suitable for use under the condition of low temperature; it has simple production process, low production cost, good the economical efficiency and wide popularization and application prospect.    DETAILED DESCRIPTION - A method for producing biodiesel by using seeds of soapberry comprises: (1) adding seeds of soapberry in the reactor with cutting and mixing device after being selected, dried, and crushed; (2) adding the dried and crushed seeds of soapberry in the reactor with fast cutting and mixing device, adding short chain alcohol and fatty acid methyl ester, cutting and mixing for 1-4 hours to form uniform suspending liquid; (3) adding alkalescent material in suspending liquid (2) to be mixed for 1-4 hours; (4) dissolving KOH or NaOH in the methyl alcohol to prepare KOH or NaOH methanol solution with mass percentage of 8-10% as the catalyst, adding in the suspending liquid (3), reflowing for 0.5-4 hours at 50-120 degrees C; (5) reducing the temperature to 40 degrees C, obtaining the separated filtrate by pressure filtration and using the filter cake for other purpose; (6) standing the separated filtrate and separating to remove the subsidiary product such as glycerin on the lower layer, and obtaining the crude product of biodiesel; (7) distilling the crude product of biodiesel at normal pressure, recovering the short chain alcohol; and (8) obtaining the standard biodiesel by atmospheric distillation.