NOVELTY - The method comprises pre-esterifying (S0) raw material oil, mixing (S1) the raw material oil with medium-short-chain alcohol, finishing the pre-esterification reaction under the catalysis of concentrated sulfuric acid and the ester exchange reaction under the action of a homogeneous alkali catalyst (0.1-3%), separating (S2) the reaction solution with the ester exchange reaction finished for obtaining crude biodiesel, adding (S3) a solid neutralizing agent into the crude biodiesel to react for 10-60 minutes, and separating (S4) solid neutralizing agent for obtaining biodiesel.    USE - The method is useful for producing biodiesel.    ADVANTAGE - The method is capable of simply producing the biodiesel with high yield.    DETAILED DESCRIPTION - The method comprises pre-esterifying raw material oil, mixing the raw material oil with medium-short-chain alcohol, finishing the pre-esterification reaction under the catalysis of concentrated sulfuric acid and the ester exchange reaction under the action of a homogeneous alkali catalyst (0.1-3%), separating the reaction solution with the ester exchange reaction finished for obtaining crude biodiesel, adding a solid neutralizing agent into the crude biodiesel to react for 10-60 minutes, and separating solid neutralizing agent for obtaining biodiesel. The raw material oil is jatropha curcas oil, colleseed oil, corn oil, soybean oil, castor oil, coconut oil, peanut oil, swill-cooked dirty oil, lard oil and alga oil. An acid value of the raw material oil is more than 1 mgKOH/g. A mol ratio of the medium-short-chain alcohol to the raw material oil is 3.5:1-30:1. The solid neutralizing agent is acid earth, strong acid type resin and modified zeolite molecular sieve. The modified zeolite molecular sieve is prepared by soaking zeolite molecular sieve in hydrochloric acid or sulfuric acid solution of 0.3-1.5 mol.L-1 for 1-24 hours and then orderly separating, washing and drying for obtaining the modified zeolite molecular sieve.    DESCRIPTION OF DRAWING(S) - The figure shows a flowchart of a method for producing biodiesel.    pre-esterifying raw material oil (S0)    Mixing the raw material oil with medium-short-chain alcohol (S1)    Separating the reaction solution with the ester exchange reaction finished for obtaining crude biodiesel (S2)    Adding a solid neutralizing agent into the crude biodiesel (S3)    Separating solid neutralizing agent for obtaining biodiesel. (S4)