The Terwen's reduction method and the methods reported by Heilmeyer, Krebs and Watson were fully observed. And the results were as follows. 1. Urobilin was completely reduced to urobilinogen within 2 hours by the Terwen's method, and the highest uroblinogen value was observed on the mixed rate of the materials and the reducing agents in 40:5:5. The materials should be stored, under the isolation of air and light, at the low temperature as possible and there was a limitation for the preserved time. 2. The optimal range of pH for the extraction of urobilinogen into the solvont. 3. It was demonstrated that petroleum ether was the best solvent for the extraction of urobilinogen since the comparative studies on the various solvent, especially between ether and petroleum ether. 4. The composition of regent needed the concentration of 0.3% P-dimethylaminobenzaldehyde on the use of 60% hydrochloric acid and of 1% P-dimethylaminobenzaldehyde on the use of 50% hydrochloric acid. 5. The shaking process for one minute was needed till the addition of sodium acetate after the addition of regents, urobilinogen in the solvent was extracted into hydrochloric acid in the regent and the reaction was performed in the water layer by the above treatment. The progress of aldehyde reaction on this occasion was considerably quantitative. 6. The significance of adding sodium acetate was to shift to nearly the pH 4 after the terminal reaction and was to remove the coloration by indole body, with bringing the coloration of urobilinogen up to the highest and keeping the stability of it. 7. The influence of indole, indican, P.A.S. and sulfonamid derivatives shown the similar reaction in the qualitative test could be eliminated on the quantitive method.