Hydrotalcite was prepared by co-precipitation of magnesium and aluminum nitrate solution.After calcination

the hydrotalcite was converted to Mg-Al composite oxides.The transesterification of rapeseed oil was carried out by using treated Mg-Al composite oxides as catalyst.Through orthogonal analysis

the optimum reaction conditions obtained for the transesterification were set at temperature 65 ℃

mole ratio of methanol to rapeseed oil 6∶1

reaction time 3 h

and catalyst dosage 2% (on rapeseed oil mass).The yield of fatty acid methyl ester (biodiesel fuel) was 95.7%.The fluidity of the biodiesel fuel at low temperature was much better than that of No.0 diesel fuel and the flash point was as high as 170 ℃ with a sound oxidation stability.Other principal physicochemical properties of the biodiesl fuel were similar to that of No.0 diesel fuel.The biodiesel fuel could be blended with No.0 diesel fuel at any ratio.