Production technology for preparing biodiesel from tallowseed oil

The invention relates to the production technology used Chinese tallow as raw material to make biological diesel oil. It mixes low carbon alcohol with Chinese tallow to do ester interchange reaction by catalyst at certain temperature. After it has finished, the upper layer is the coarse biological diesel oil; and the under is the mixture of glycerol and low carbon alcohol. The upper layer coarse product is purified at the following conditions: the mol ratio of the low carbon alcohol and Chinese tallow is 3-40:1; the catalyst can be any one of base, acid, enzyme, and solid magnetism catalysis; the temperature of ester interchange is 20-120 centigrade degree; and the weight of the added catalyst is 0.1%-10.0% of the Chinese tallow. The advantages of the invention are that the solidifying point of the biological diesel oil is -10 centigrade degree, so it is not easy to coagulate; it has rich raw material and simple technological process; and its by-product can be used circularly.