NOVELTY - Water-soluble metal salt is dissolved in de-ionized water, to obtain aqueous solution. Then, surfactant and aqueous solution of basic compound are added into mixture, pH is regulated, stirred and aged. The precipitate is washed with scrub solution or de-ionized water, to remove harmful anion. The metal oxide is fed into filtering device, washed with sulfuric acid solution, and the dosage amount of sulfuric acid solution is controlled at 5-20 ml/g of metal oxide. Then, the reaction mixture is dried and sintered at, to obtain solid catalyst acidulated by sulfuric acid.    USE - Preparation of acidulated solid catalyst for manufacture of biodiesel.    ADVANTAGE - The method simply, economically and efficiently manufactures catalyst having high catalytic activity and recyclability. The biodiesel is manufactured simply and environmental friendly using the catalyst. The biodiesel has excellent luster and high purity.    DETAILED DESCRIPTION - Water-soluble metal salt is dissolved in de-ionized water, to obtain aqueous solution having viscosity of 0.01-10 mol/L. Then, surfactant (0.5-1.5%) is added, stirred uniformly, and aqueous solution of basic compound having viscosity of 0.01-10 mol/L is mixed with the mixture, to regulate the pH of the reaction mixture to 7-12, such that the metallic ion is completely precipitated. The obtained mixture is stirred for 0.5-4.8 hour, aged for 2-48 hours and the obtained precipitate is washed with scrub solution or de-ionized water for 3-5 times, to remove harmful anion. The metal oxide is fed into filtering device, washed with sulfuric acid solution (0.01-2.0 mol/L), and the dosage amount of sulfuric acid solution is controlled at 5-20 ml/g of metal oxide. Then, the reaction mixture is dried at 40-120 degrees C for 0.5-24 hours and sintered at 300-800 degrees C for 1-8 hours, to obtain solid catalyst acidulated by sulfuric acid. The water-soluble metal salt is salt of zirconium ion (Zr4+), titanium ion (Ti4+), zinc ion (Zn4+), ferric ion (Fe3+), aluminum ion (Al3+), silicon ion (Si4+), tungsten ion (W4+), vanadium ion (V4+), chromium ion (Cr2+), cobalt ion (Co2+), cuprous ion (Cu2+), platinum ion (Pt2+), nickel ion (Ni2+), manganese ion (Mn2+), yttrium ion (Y3+), molybdenum ion (Mo4+), palladium ion (Pd2+), cadmium ion (Cd2+) or protactinium ion (Pa3+). The acid radical of salt is sulfate radical, nitrate radical, phosphate radical, chlorate or oxy-chlorate. The surfactant is diethanolameine, trolamine, fatty alcohol-polyoxyethylene (3)ether, fatty alcohol-polyoxyethylene (9)ether, sodium dodecyl benzene sulfonate, sodium stearate, sodium dodecyl sulfate, Tween (RTM: surfactant) or oleic acid. The basic compound is ammonia, carbamide, ammonium hydrogen carbonate, ammonium carbonate, sodium hydroxide, potassium hydroxide, potassium carbonate, potassium bicarbonate, sodium carbonate or sodium bicarbonate. The scrub solution is aqueous solution of ammonium carbonate, ammonium hydrogen carbonate or ammonium nitrate. The scrub solution has viscosity of 0.01-5 mol/L. The alcohol is methanol, ethanol, propanol or butanol.